Commit Graph

288 Commits

Author SHA1 Message Date
Evan Cheng
8239daf7c8 Two sets of changes. Sorry they are intermingled.
1. Fix pre-ra scheduler so it doesn't try to push instructions above calls to
   "optimize for latency". Call instructions don't have the right latency and
   this is more likely to use introduce spills.
2. Fix if-converter cost function. For ARM, it should use instruction latencies,
   not # of micro-ops since multi-latency instructions is completely executed
   even when the predicate is false. Also, some instruction will be "slower"
   when they are predicated due to the register def becoming implicit input.
   rdar://8598427


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@118135 91177308-0d34-0410-b5e6-96231b3b80d8
2010-11-03 00:45:17 +00:00
Jim Grosbach
ab3d00e535 Revert r114340 (improvements in Darwin function prologue/epilogue), as it broke
assumptions about stack layout. Specifically, LR must be saved next to FP.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@118026 91177308-0d34-0410-b5e6-96231b3b80d8
2010-11-02 17:35:25 +00:00
Bob Wilson
f74a429816 Overhaul memory barriers in the ARM backend. Radar 8601999.
There were a number of issues to fix up here:
* The "device" argument of the llvm.memory.barrier intrinsic should be
used to distinguish the "Full System" domain from the "Inner Shareable"
domain.  It has nothing to do with using DMB vs. DSB instructions.
* The compiler should never need to emit DSB instructions.  Remove the
ARMISD::SYNCBARRIER node and also remove the instruction patterns for DSB.
* Merge the separate DMB/DSB instructions for options only used for the
disassembler with the default DMB/DSB instructions.  Add the default
"full system" option ARM_MB::SY to the ARM_MB::MemBOpt enum.
* Add a separate ARMISD::MEMBARRIER_MCR node for subtargets that implement
a data memory barrier using the MCR instruction.
* Fix up encodings for these instructions (except MCR).
I also updated the tests and added a few new ones to check for DMB options
that were not currently being exercised.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@117756 91177308-0d34-0410-b5e6-96231b3b80d8
2010-10-30 00:54:37 +00:00
Evan Cheng
089751535d Avoiding overly aggressive latency scheduling. If the two nodes share an
operand and one of them has a single use that is a live out copy, favor the
one that is live out. Otherwise it will be difficult to eliminate the copy
if the instruction is a loop induction variable update. e.g.

BB:
sub r1, r3, #1
str r0, [r2, r3]
mov r3, r1
cmp
bne BB

=>

BB:
str r0, [r2, r3]
sub r3, r3, #1
cmp
bne BB

This fixed the recent 256.bzip2 regression.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@117675 91177308-0d34-0410-b5e6-96231b3b80d8
2010-10-29 18:09:28 +00:00
Evan Cheng
134982daa9 More accurate estimate / tracking of register pressure.
- Initial register pressure in the loop should be all the live defs into the
  loop. Not just those from loop preheader which is often empty.
- When an instruction is hoisted, update register pressure from loop preheader
  to the original BB.
- Treat only use of a virtual register as kill since the code is still SSA.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116956 91177308-0d34-0410-b5e6-96231b3b80d8
2010-10-20 22:03:58 +00:00
Dale Johannesen
e4d31593c5 Fix crash introduced in 116852. 8573915.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116955 91177308-0d34-0410-b5e6-96231b3b80d8
2010-10-20 22:03:37 +00:00
Dale Johannesen
575cd148ce Enable using vdup for vector constants which are splat of
integers by default, and remove the controlling flag, now
that LICM will hoist such vdup's.  8003375.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116852 91177308-0d34-0410-b5e6-96231b3b80d8
2010-10-19 20:00:17 +00:00
Evan Cheng
2312842de0 Re-enable register pressure aware machine licm with fixes. Hoist() may have
erased the instruction during LICM so UpdateRegPressureAfter() should not
reference it afterwards.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116845 91177308-0d34-0410-b5e6-96231b3b80d8
2010-10-19 18:58:51 +00:00
Daniel Dunbar
9869413802 Revert r116781 "- Add a hook for target to determine whether an instruction def
is", which breaks some nightly tests.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116816 91177308-0d34-0410-b5e6-96231b3b80d8
2010-10-19 17:14:24 +00:00
Evan Cheng
11e8b74a7a - Add a hook for target to determine whether an instruction def is
"long latency" enough to hoist even if it may increase spilling. Reloading
  a value from spill slot is often cheaper than performing an expensive
  computation in the loop. For X86, that means machine LICM will hoist
  SQRT, DIV, etc. ARM will be somewhat aggressive with VFP and NEON
  instructions.
- Enable register pressure aware machine LICM by default.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116781 91177308-0d34-0410-b5e6-96231b3b80d8
2010-10-19 00:55:07 +00:00
Bob Wilson
7d24705f65 Change register allocation order for ARM VFP and NEON registers to put the
callee-saved registers at the end of the lists.  Also prefer to avoid using
the low registers that are in register subclasses required by certain
instructions, so that those registers will more likely be available when needed.
This change makes a huge improvement in spilling in some cases.  Thanks to
Jakob for helping me realize the problem.

Most of this patch is fixing the testsuite.  There are quite a few places
where we're checking for specific registers.  I changed those to wildcards
in places where that doesn't weaken the tests.  The spill-q.ll and
thumb2-spill-q.ll tests stopped spilling with this change, so I added a bunch
of live values to force spills on those tests.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116055 91177308-0d34-0410-b5e6-96231b3b80d8
2010-10-08 06:15:13 +00:00
Owen Anderson
8614167572 Enable target-specific mul-lowering on ARM, even at -Os. Remove a test that this makes
irrelevant, but add a new test for the new, improved functionality.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114494 91177308-0d34-0410-b5e6-96231b3b80d8
2010-09-21 22:51:46 +00:00
Jim Grosbach
1dc335a79f Simplify ARM callee-saved register handling by removing the distinction
between the high and low registers for prologue/epilogue code. This was
a Darwin-only thing that wasn't providing a realistic benefit anymore.
Combining the save areas simplifies the compiler code and results in better
ARM/Thumb2 codegen.

For example, previously we would generate code like:
        push    {r4, r5, r6, r7, lr}
        add     r7, sp, #12
        stmdb   sp!, {r8, r10, r11}
With this change, we combine the register saves and generate:
        push    {r4, r5, r6, r7, r8, r10, r11, lr}
        add     r7, sp, #12

rdar://8445635



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114340 91177308-0d34-0410-b5e6-96231b3b80d8
2010-09-20 19:32:20 +00:00
Jim Grosbach
e6be85e9ff Teach the (non-MC) instruction printer to use the cannonical names for push/pop,
and shift instructions on ARM. Update the tests to match.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114230 91177308-0d34-0410-b5e6-96231b3b80d8
2010-09-17 22:36:38 +00:00
Jim Grosbach
1aaf4cb393 Move thumb2 tests to the thumb2 directory
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114206 91177308-0d34-0410-b5e6-96231b3b80d8
2010-09-17 20:34:09 +00:00
Evan Cheng
3ef1c8759a Teach if-converter to be more careful with predicating instructions that would
take multiple cycles to decode.
For the current if-converter clients (actually only ARM), the instructions that
are predicated on false are not nops. They would still take machine cycles to
decode. Micro-coded instructions such as LDM / STM can potentially take multiple
cycles to decode. If-converter should take treat them as non-micro-coded
simple instructions.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@113570 91177308-0d34-0410-b5e6-96231b3b80d8
2010-09-10 01:29:16 +00:00
Bob Wilson
0f1e9457a5 Fix NEON VLD pseudo instruction itineraries that were incorrectly copied from
the VST pseudos.  The VLD/VST scheduling still needs work (see pr6722), but
at least we shouldn't confuse the loads with the stores.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@113473 91177308-0d34-0410-b5e6-96231b3b80d8
2010-09-09 05:40:26 +00:00
Jim Grosbach
65482b1bb8 Re-apply r112883:
"For ARM stack frames that utilize variable sized objects and have either
large local stack areas or require dynamic stack realignment, allocate a
base register via which to access the local frame. This allows efficient
access to frame indices not accessible via the FP (either due to being out
of range or due to dynamic realignment) or the SP (due to variable sized
object allocation). In particular, this greatly improves efficiency of access
to spill slots in Thumb functions which contain VLAs."

r112986 fixed a latent bug exposed by the above.




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112989 91177308-0d34-0410-b5e6-96231b3b80d8
2010-09-03 18:37:12 +00:00
Daniel Dunbar
6a8700301c Revert "For ARM stack frames that utilize variable sized objects and have either", it is breaking oggenc with Clang for ARMv6.
This reverts commit 8d6e29cfda270be483abf638850311670829ee65.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112962 91177308-0d34-0410-b5e6-96231b3b80d8
2010-09-03 15:26:42 +00:00
Jim Grosbach
1755b3964f For ARM stack frames that utilize variable sized objects and have either
large local stack areas or require dynamic stack realignment, allocate a
base register via which to access the local frame. This allows efficient
access to frame indices not accessible via the FP (either due to being out
of range or due to dynamic realignment) or the SP (due to variable sized
object allocation). In particular, this greatly improves efficiency of access
to spill slots in Thumb functions which contain VLAs.

rdar://7352504
rdar://8374540
rdar://8355680



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112883 91177308-0d34-0410-b5e6-96231b3b80d8
2010-09-02 22:29:01 +00:00
Jim Grosbach
e7c1416263 Now that register allocation properly considers reserved regs, simplify the
ARM register class allocation order functions to take advantage of that.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112841 91177308-0d34-0410-b5e6-96231b3b80d8
2010-09-02 18:14:29 +00:00
Chris Lattner
5bcb8a6112 temporarily revert r112664, it is causing a decoding conflict, and
the testcases should be merged.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112711 91177308-0d34-0410-b5e6-96231b3b80d8
2010-09-01 16:00:50 +00:00
Bill Wendling
43a6c5e2fc We have a chance for an optimization. Consider this code:
int x(int t) {
  if (t & 256)
    return -26;
  return 0;
}

We generate this:

     tst.w   r0, #256
     mvn     r0, #25
     it      eq
     moveq   r0, #0

while gcc generates this:

     ands    r0, r0, #256
     it      ne
     mvnne   r0, #25
     bx      lr

Scandalous really!

During ISel time, we can look for this particular pattern. One where we have a
"MOVCC" that uses the flag off of a CMPZ that itself is comparing an AND
instruction to 0. Something like this (greatly simplified):

  %r0 = ISD::AND ...
  ARMISD::CMPZ %r0, 0         @ sets [CPSR]
  %r0 = ARMISD::MOVCC 0, -26  @ reads [CPSR]

All we have to do is convert the "ISD::AND" into an "ARM::ANDS" that sets [CPSR]
when it's zero. The zero value will all ready be in the %r0 register and we only
need to change it if the AND wasn't zero. Easy!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112664 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-31 22:41:22 +00:00
Bob Wilson
7a9ef44b3b Add alignment arguments to all the NEON load/store intrinsics.
Update all the tests using those intrinsics and add support for
auto-upgrading bitcode files with the old versions of the intrinsics.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112271 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-27 17:13:24 +00:00
Daniel Dunbar
3cc3283fcb ARM/Thumb2: Fix a misselect in getARMCmp, when attempting to adjust a signed
comparison that would overflow.
 - The other under/overflow cases can't actually happen because the immediates
   which would trigger them are legal (so we don't enter this code), but
   adjusted the style to make it clear the transform is always valid.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112053 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-25 16:58:05 +00:00
Bob Wilson
f955f290c9 Change ARM PKHTB and PKHBT instructions to use a shift_imm operand to avoid
printing "lsl #0".  This fixes the remaining parts of pr7792.  Make
corresponding changes for encoding/decoding these instructions.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111251 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-17 17:23:19 +00:00
Bob Wilson
dc66edaced Generalize a pattern for PKHTB: an SRL of 16-31 bits will guarantee
that the high halfword is zero.  The shift need not be exactly 16 bits.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111196 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-16 22:26:55 +00:00
Bob Wilson
b05b80160a Convert test to FileCheck.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111195 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-16 22:21:13 +00:00
Bob Wilson
703af3ab12 Temporarily disable tail calls on ARM to work around some linker problems.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111050 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-13 22:43:33 +00:00
Jim Grosbach
b5aa11f2d6 fix silly typo
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110831 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-11 17:32:46 +00:00
Jim Grosbach
7166e622d7 Add a target triple, as the runtime library invocation varies a bit by
platform. It's apparently "bl __muldf3" on linux, for example. Since that's
not what we're checking here, it's more robust to just force a triple. We
just wwant to check that the inline FP instructions are only generated
on cpus that have them."



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110830 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-11 17:31:12 +00:00
Dan Gohman
3cc5d13f58 Temporarily disable some failing tests, until they can be
properly investigated.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110825 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-11 16:36:07 +00:00
Jim Grosbach
fcba5e6b64 cortex m4 has floating point support, but only single precision.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110810 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-11 15:44:15 +00:00
Evan Cheng
7b4d31176e Report error if codegen tries to instantiate a ARM target when the cpu does support it. e.g. cortex-m* processors.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110798 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-11 07:17:46 +00:00
Evan Cheng
11db068721 - Add subtarget feature -mattr=+db which determine whether an ARM cpu has the
memory and synchronization barrier dmb and dsb instructions.
- Change instruction names to something more sensible (matching name of actual
  instructions).
- Added tests for memory barrier codegen.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110785 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-11 06:22:01 +00:00
Evan Cheng
ac096808a3 Re-apply r110655 with fixes. Epilogue must restore sp from fp if the function stack frame has a var-sized object.
Also added a test case to check for the added benefit of this patch: it's optimizing away the unnecessary restore of sp from fp for some non-leaf functions.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110707 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-10 19:30:19 +00:00
Jim Grosbach
6ccfc507dc Many Thumb2 instructions can reference the full ARM register set (i.e.,
have 4 bits per register in the operand encoding), but have undefined
behavior when the operand value is 13 or 15 (SP and PC, respectively).
The trivial coalescer in linear scan sometimes will merge a copy from
SP into a subsequent instruction which uses the copy, and if that
instruction cannot legally reference SP, we get bad code such as:
  mls r0,r9,r0,sp
instead of:
  mov r2, sp
  mls r0, r9, r0, r2

This patch adds a new register class for use by Thumb2 that excludes
the problematic registers (SP and PC) and is used instead of GPR
for those operands which cannot legally reference PC or SP. The
trivial coalescer explicitly requires that the register class
of the destination for the COPY instruction contain the source
register for the COPY to be considered for coalescing. This prevents
errant instructions like that above.

PR7499




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@109842 91177308-0d34-0410-b5e6-96231b3b80d8
2010-07-30 02:41:01 +00:00
Dale Johannesen
f630c712b1 Implement vector constants which are splat of
integers with mov + vdup.  8003375.  This is
currently disabled by default because LICM will
not hoist a VDUP, so it pessimizes the code if
the construct occurs inside a loop (8248029).



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@109799 91177308-0d34-0410-b5e6-96231b3b80d8
2010-07-29 20:10:08 +00:00
Jim Grosbach
f27ca42552 update tests for smarter BIC usage
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@108846 91177308-0d34-0410-b5e6-96231b3b80d8
2010-07-20 16:16:48 +00:00
Jim Grosbach
5423856e44 Add combiner patterns to more effectively utilize the BFI (bitfield insert)
instruction for non-constant operands. This includes the case referenced
in the README.txt regarding a bitfield copy.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@108608 91177308-0d34-0410-b5e6-96231b3b80d8
2010-07-17 03:30:54 +00:00
Jim Grosbach
469bbdb597 Add basic support to code-gen the ARM/Thumb2 bit-field insert (BFI) instruction
and a combine pattern to use it for setting a bit-field to a constant
value. More to come for non-constant stores.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@108570 91177308-0d34-0410-b5e6-96231b3b80d8
2010-07-16 23:05:05 +00:00
Jim Grosbach
502e0aa628 Improve 64-subtraction of immediates when parts of the immediate can fit
in the literal field of an instruction. E.g.,
long long foo(long long a) {
  return a - 734439407618LL;
}

rdar://7038284



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@108339 91177308-0d34-0410-b5e6-96231b3b80d8
2010-07-14 17:45:16 +00:00
Bob Wilson
7a52e65ca6 Fix test to appease the buildbots.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@108334 91177308-0d34-0410-b5e6-96231b3b80d8
2010-07-14 16:43:47 +00:00
Bob Wilson
a0148c360e Print "dregpair" NEON operands with a space between them, for readability and
consistency with other instructions that have lists of register operands.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107944 91177308-0d34-0410-b5e6-96231b3b80d8
2010-07-09 00:47:20 +00:00
Dale Johannesen
7835f1fcdb Changes to ARM tail calls, mostly cosmetic.
Add explicit testcases for tail calls within the same module.
Duplicate some code to humor those who think .w doesn't apply on ARM.
Leave this disabled on Thumb1, and add some comments explaining why it's hard
and won't gain much.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107851 91177308-0d34-0410-b5e6-96231b3b80d8
2010-07-08 01:18:23 +00:00
Evan Cheng
c36b5b9730 PR7503: uxtb16 is not available for ARMv7-M. Patch by Brian G. Lucas.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107122 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-29 05:38:36 +00:00
Bob Wilson
8eab75f390 Reapply my if-conversion cleanup from svn r106939 with fixes.
There are 2 changes relative to the previous version of the patch:

1) For the "simple" if-conversion case, there's no need to worry about
RemoveExtraEdges not handling an unanalyzable branch.  Predicated terminators
are ignored in this context, so RemoveExtraEdges does the right thing.
This might break someday if we ever treat indirect branches (BRIND) as
predicable, but for now, I just removed this part of the patch, because
in the case where we do not add an unconditional branch, we rely on keeping
the fall-through edge to CvtBBI (which is empty after this transformation).

The change relative to the previous patch is:

@@ -1036,10 +1036,6 @@
     IterIfcvt = false;
   }
 
-  // RemoveExtraEdges won't work if the block has an unanalyzable branch,
-  // which is typically the case for IfConvertSimple, so explicitly remove
-  // CvtBBI as a successor.
-  BBI.BB->removeSuccessor(CvtBBI->BB);
   RemoveExtraEdges(BBI);
 
   // Update block info. BB can be iteratively if-converted.


2) My patch exposed a bug in the code for merging the tail of a "diamond",
which had previously never been exercised.  The code was simply checking that
the tail had a single predecessor, but there was a case in
MultiSource/Benchmarks/VersaBench/dbms where that single predecessor was
neither edge of the diamond.  I added the following change to check for
that:

@@ -1276,7 +1276,18 @@
   // tail, add a unconditional branch to it.
   if (TailBB) {
     BBInfo TailBBI = BBAnalysis[TailBB->getNumber()];
-    if (TailBB->pred_size() == 1 && !TailBBI.HasFallThrough) {
+    bool CanMergeTail = !TailBBI.HasFallThrough;
+    // There may still be a fall-through edge from BBI1 or BBI2 to TailBB;
+    // check if there are any other predecessors besides those.
+    unsigned NumPreds = TailBB->pred_size();
+    if (NumPreds > 1)
+      CanMergeTail = false;
+    else if (NumPreds == 1 && CanMergeTail) {
+      MachineBasicBlock::pred_iterator PI = TailBB->pred_begin();
+      if (*PI != BBI1->BB && *PI != BBI2->BB)
+        CanMergeTail = false;
+    }
+    if (CanMergeTail) {
       MergeBlocks(BBI, TailBBI);
       TailBBI.IsDone = true;
     } else {

With these fixes, I was able to run all the SingleSource and MultiSource
tests successfully.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107110 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-29 00:55:23 +00:00
Bob Wilson
de4fe23139 Revert my if-conversion cleanup since it caused a bunch of nightly test
regressions.

--- Reverse-merging r106939 into '.':
U    test/CodeGen/Thumb2/thumb2-ifcvt3.ll
U    lib/CodeGen/IfConversion.cpp


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106951 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-26 17:47:06 +00:00
Eli Friedman
56df4a079b Remove bogus test.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106941 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-26 04:59:56 +00:00
Bob Wilson
ccd9bcca14 Clean up some problems with extra CFG edges being introduced during
if-conversion.  The RemoveExtraEdges function doesn't work for blocks that
end with unanalyzable branches, so in those cases, the "extra" edges must
be explicitly removed.  The CopyAndPredicateBlock and MergeBlocks methods
can also avoid copying successor edges due to branches that have already
been removed.  The latter case is especially helpful when MergeBlocks is
called for handling "diamond" if-conversions, where otherwise you can end
up with some weird intermediate states in the CFG.  Unfortunately I've
been unable to find cases where this cleanup actually makes a significant
difference in the code.  There is one test where we manage to remove an
empty block at the end of a function.  Radar 6911268.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106939 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-26 04:27:33 +00:00