7330 Commits

Author SHA1 Message Date
Elena Demikhovsky
3575222175 Special calling conventions for Intel OpenCL built-in library.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166566 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-24 14:46:16 +00:00
Michael Liao
1a5cc710ee Teach DAG combine to fold (buildvec (Xint2fp x)) to (Xint2fp (buildvec x))
- If more than 1 elemennts are defined and target supports the vectorized
  conversion, use the vectorized one instead to reduce the strength on
  conversion operation.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166546 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-24 04:14:18 +00:00
Michael Liao
991b6a22b6 Add custom conversion from v2u32 to v2f32 in 32-bit mode
- As there's no 64-bit GPRs in 32-bit mode, a custom conversion from v2u32 to
  v2f32 is added to improve the efficiency of the code generated.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166545 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-24 04:09:32 +00:00
Akira Hatanaka
2ef5bd3ba6 [mips] Make sure sret argument is returned in register V0.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166539 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-24 02:10:54 +00:00
Rafael Espindola
847a9c6d77 Change x86_fastcallcc to require inreg markers. This allows it to known
the difference from "int x" (which should go in registers and
"struct y {int x;}" (which should not).

Clang will be updated in the next patches.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166536 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-24 01:58:48 +00:00
Michael Liao
0787274b70 Fix PR14161
- Check index being extracted to be constant 0 before simplfiying.
  Otherwise, retain the original sequence.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166504 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-23 21:40:15 +00:00
Michael Liao
d9d09600ee Enable lowering ZERO_EXTEND/ANY_EXTEND to PMOVZX from SSE4.1
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166486 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-23 17:34:00 +00:00
Reed Kotler
293e5d0e0a implement setXX patterns
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166459 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-23 01:35:48 +00:00
Bill Wendling
8f47fc8f00 When a block ends in an indirect branch, add its successors to the machine basic block.
The CFG of the machine function needs to know that the targets of the indirect
branch are successors to the indirect branch.
<rdar://problem/12529625>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166448 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-22 23:30:04 +00:00
Akira Hatanaka
30580cea43 [mips] Use 64-bit registers to return an sret pointer if target ABI is N64.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166344 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-19 22:11:40 +00:00
Akira Hatanaka
2b861be96e [mips] Add code to do tail call optimization.
Currently, it is enabled only if option "enable-mips-tail-calls" is given and
all of the callee's arguments are passed in registers.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166342 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-19 21:47:33 +00:00
Shuxin Yang
970755e519 This patch is to fix radar://8426430. It is about llvm support of __builtin_debugtrap()
which is supposed to consistently raise SIGTRAP across all systems. In contrast,
__builtin_trap() behave differently on different systems. e.g. it raises SIGTRAP on ARM, and
SIGILL on X86. The purpose of __builtin_debugtrap() is to consistently provide "trap"
functionality, in the mean time preserve the compatibility with on gcc on __builtin_trap().

  The X86 backend is already able to handle debugtrap(). This patch is to:
  1) make front-end recognize "__builtin_debugtrap()" (emboddied in the one-line change to Clang).
  2) In DAG legalization phase, by default, "debugtrap" will be replaced with "trap", which
     make the __builtin_debugtrap() "available" to all existing ports without the hassle of
     changing their code.
  3) If trap-function is specified (via -trap-func=xyz to llc), both __builtin_debugtrap() and
     __builtin_trap() will be expanded into the function call of the specified trap function.
    This behavior may need change in the future.

  The provided testing-case is to make sure 2) and 3) are working for ARM port, and we
already have a testing case for x86. 


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166300 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-19 20:11:16 +00:00
Michael Liao
facace808c Lower BUILD_VECTOR to SHUFFLE + INSERT_VECTOR_ELT for X86
- If INSERT_VECTOR_ELT is supported (above SSE2, either by custom
  sequence of legal insn), transform BUILD_VECTOR into SHUFFLE +
  INSERT_VECTOR_ELT if most of elements could be built from SHUFFLE with few
  (so far 1) elements being inserted.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166288 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-19 17:15:18 +00:00
Stepan Dyatkovskiy
0d3c8d5d16 ARM:
Removed extra stack frame object for fixed byval arguments,
VarArgsStyleRegisters invocation was reworked due to some improper usage in
past. PR14099 also demonstrates it.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166273 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-19 08:23:06 +00:00
Sebastian Pop
83ba06afa8 Clear unknown mem ops when merging stack slots (pr14090)
When merging stack slots, if StackColoring::remapInstructions gets a
value back from GetUnderlyingObject that it does not know about or is
not itself a stack slot, clear the memory operand in case it aliases
the merged slot. This prevents the introduction of incorrect aliasing
information.

Author:    Matthew Curtis <mcurtis@codeaurora.org>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166216 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-18 19:53:48 +00:00
Nadav Rotem
1c5bf3f429 In SimplifySelectOps we pulled two loads through a select node despite the fact that one was dependent on the other.
rdar://12513091



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166196 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-18 18:06:48 +00:00
Ulrich Weigand
6c28a7eec8 This patch fixes failures in the SingleSource/Regression/C/uint64_to_float
test case on PowerPC caused by rounding errors when converting from a 64-bit
integer to a single-precision floating point. The reason for this are
double-rounding effects, since on PowerPC we have to convert to an
intermediate double-precision value first, which gets rounded to the
final single-precision result.

The patch fixes the problem by preparing the 64-bit integer so that the
first conversion step to double-precision will always be exact, and the
final rounding step will result in the correctly-rounded single-precision
result.  The generated code sequence is equivalent to what GCC would generate.

When -enable-unsafe-fp-math is in effect, that extra effort is omitted
and we accept possible rounding errors (just like GCC does as well).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166178 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-18 13:16:11 +00:00
Michael Liao
07edaf3801 Revert part of r166049 back and enable test case in r166125.
- Folding (trunc (concat ... X )) to (concat ... (trunc X) ...) is valid
  when '...' are all 'undef's.
- r166125 relies on this transformation.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166155 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-17 23:45:54 +00:00
Michael Liao
6e0c2b36d6 Disable extract-concat test case temporarily
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166141 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-17 23:08:19 +00:00
Michael Liao
4031e9018b Revert r166049
- In general, it's unsafe for this transformation.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166135 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-17 22:41:15 +00:00
Reed Kotler
95a2bb4cdf Add conditional branch instructions and their patterns.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166134 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-17 22:29:54 +00:00
Michael Liao
13429e224c Teach DAG combine to fold (extract_subvec (concat v1, ..) i) to v_i
- If the extracted vector has the same type of all vectored being concatenated
  together, it should be simplified directly into v_i, where i is the index of
  the element being extracted.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166125 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-17 20:48:33 +00:00
Anton Korobeynikov
e4b33a115b Fix fallout from RegInfo => FrameLowering refactoring on MSP430.
Patch by Job Noorman!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166108 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-17 17:37:11 +00:00
Michael Liao
281ae5abf5 Fix setjmp on models with non-Small code model nor non-Static relocation model
- MBB address is only valid as an immediate value in Small & Static
  code/relocation models. On other models, LEA is needed to load IP address of
  the restore MBB.
- A minor fix of MBB in MC lowering is added as well to enable target
  relocation flag being propagated into MC.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166084 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-17 02:22:27 +00:00
Jakob Stoklund Olesen
320db3f805 Avoid rematerializing a redef immediately after the old def.
PR14098 contains an example where we would rematerialize a MOV8ri
immediately after the original instruction:

  %vreg7:sub_8bit<def> = MOV8ri 9; GR32_ABCD:%vreg7
  %vreg22:sub_8bit<def> = MOV8ri 9; GR32_ABCD:%vreg7

Besides being pointless, it is also wrong since the original instruction
only redefines part of the register, and the value read by the new
instruction is wrong.

The problem was the LiveRangeEdit::allUsesAvailableAt() didn't
special-case OrigIdx == UseIdx and found the wrong SSA value.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166068 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-16 22:51:58 +00:00
Jakob Stoklund Olesen
cdcdfd2cab Revert r166046 "Switch back to the old coalescer for now to fix the 32 bit bit"
A fix for PR14098, including the test case is in the next commit.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166067 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-16 22:51:55 +00:00
Michael Liao
272ea03239 Teach DAG combine to fold (trunc (fptoXi x)) to (fptoXi x)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166049 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-16 19:38:35 +00:00
Rafael Espindola
6f7cccd2e2 Switch back to the old coalescer for now to fix the 32 bit bit
llvm+clang+compiler-rt bootstrap.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166046 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-16 19:34:06 +00:00
Bill Schmidt
7a6cb15a92 This patch addresses PR13949.
For the PowerPC 64-bit ELF Linux ABI, aggregates of size less than 8
bytes are to be passed in the low-order bits ("right-adjusted") of the
doubleword register or memory slot assigned to them.  A previous patch
addressed this for aggregates passed in registers.  However, small
aggregates passed in the overflow portion of the parameter save area are
still being passed left-adjusted.

The fix is made in PPCTargetLowering::LowerCall_Darwin_Or_64SVR4 on the
caller side, and in PPCTargetLowering::LowerFormalArguments_64SVR4 on
the callee side.  The main fix on the callee side simply extends
existing logic for 1- and 2-byte objects to 1- through 7-byte objects,
and correcting a constant left over from 32-bit code.  There is also a
fix to a bogus calculation of the offset to the following argument in
the parameter save area.

On the caller side, again a constant left over from 32-bit code is
fixed.  Additionally, some code for 1, 2, and 4-byte objects is
duplicated to handle the 3, 5, 6, and 7-byte objects for SVR4 only.  The
LowerCall_Darwin_Or_64SVR4 logic is getting fairly convoluted trying to
handle both ABIs, and I propose to separate this into two functions in a
future patch, at which time the duplication can be removed.

The patch adds a new test (structsinmem.ll) to demonstrate correct
passing of structures of all seven sizes.  Eight dummy parameters are
used to force these structures to be in the overflow portion of the
parameter save area.

As a side effect, this corrects the case when aggregates passed in
registers are saved into the first eight doublewords of the parameter
save area:  Previously they were stored left-justified, and now are
properly stored right-justified.  This requires changing the expected
output of existing test case structsinregs.ll.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166022 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-16 13:30:53 +00:00
Stepan Dyatkovskiy
b52ba9f8a8 Issue:
Stack is formed improperly for long structures passed as byval arguments for
EABI mode.

If we took AAPCS reference, we can found the next statements:

A: "If the argument requires double-word alignment (8-byte), the NCRN (Next
Core Register Number) is rounded up to the next even register number." (5.5
Parameter Passing, Stage C, C.3).

B: "The alignment of an aggregate shall be the alignment of its most-aligned
component." (4.3 Composite Types, 4.3.1 Aggregates).

So if we have structure with doubles (9 double fields) and 3 Core unused
registers (r1, r2, r3): caller should use r2 and r3 registers only.
Currently r1,r2,r3 set is used, but it is invalid.

Callee VA routine should also use r2 and r3 regs only. All is ok here. This
behaviour is guessed by rounding up SP address with ADD+BFC operations.

Fix:
Main fix is in ARMTargetLowering::HandleByVal. If we detected AAPCS mode and
8 byte alignment, we waste odd registers then.

P.S.:
I also improved LDRB_POST_IMM regression test. Since ldrb instruction will
not generated by current regression test after this patch. 


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166018 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-16 07:16:47 +00:00
NAKAMURA Takumi
e26874556b Reapply r165661, Patch by Shuxin Yang <shuxin.llvm@gmail.com>.
Original message:

The attached is the fix to radar://11663049. The optimization can be outlined by following rules:

   (select (x != c), e, c) -> select (x != c), e, x),
   (select (x == c), c, e) -> select (x == c), x, e)
where the <c> is an integer constant.

 The reason for this change is that : on x86, conditional-move-from-constant needs two instructions;
however, conditional-move-from-register need only one instruction.

  While the LowerSELECT() sounds to be the most convenient place for this optimization, it turns out to be a bad place. The reason is that by replacing the constant <c> with a symbolic value, it obscure some instruction-combining opportunities which would otherwise be very easy to spot. For that reason, I have to postpone the change to last instruction-combining phase.

  The change passes the test of "make check-all -C <build-root/test" and "make -C project/test-suite/SingleSource".

Original message since r165661:

My previous change has a bug: I negated the condition code of a CMOV, and go ahead creating a new CMOV using the *ORIGINAL* condition code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166017 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-16 06:28:34 +00:00
Rafael Espindola
0cead1cfef Fix the cpu name and add -verify-machineinstrs.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166003 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-16 01:13:06 +00:00
Andrew Trick
27c28cef11 misched: Added handleMove support for updating all kill flags, not just for allocatable regs.
This is a medium term workaround until we have a more robust solution
in the form of a register liveness utility for postRA passes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166001 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-16 00:22:51 +00:00
Michael Liao
6c0e04c823 Add __builtin_setjmp/_longjmp supprt in X86 backend
- Besides used in SjLj exception handling, __builtin_setjmp/__longjmp is also
  used as a light-weight replacement of setjmp/longjmp which are used to
  implementation continuation, user-level threading, and etc. The support added
  in this patch ONLY addresses this usage and is NOT intended to support SjLj
  exception handling as zero-cost DWARF exception handling is used by default
  in X86.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165989 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-15 22:39:43 +00:00
Jim Grosbach
64ba635209 ARM: v1i64 and v2i64 VBSL intrinsic support.
rdar://12502028

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165981 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-15 21:23:40 +00:00
Andrew Trick
874c0a6ec7 Check output of the misched unit tests
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165959 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-15 20:33:14 +00:00
Rafael Espindola
32522201a8 Add a cpu to try to fix the atom builder.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165956 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-15 19:25:43 +00:00
Rafael Espindola
3da6f0392a Add testcase for pr14088.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165954 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-15 19:00:10 +00:00
Andrew Trick
bb20b24224 misched tests: add a triple to speculatively fix windows builders.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165952 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-15 18:21:08 +00:00
Andrew Trick
1e94e98b0e misched: ILP scheduler for experimental heuristics.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165950 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-15 18:02:27 +00:00
Silviu Baranga
bb1078ea13 Fixed PR13938: the ARM backend was crashing because it couldn't select a VDUPLANE node with the vector input size different from the output size. This was bacause the BUILD_VECTOR lowering code didn't check that the size of the input vector was correct for using VDUPLANE.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165929 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-15 09:41:32 +00:00
Jakob Stoklund Olesen
d86296a4ae Drop <def,dead> flags when merging into an unused lane.
The new coalescer can merge a dead def into an unused lane of an
otherwise live vector register.

Clear the <dead> flag when that happens since the flag refers to the
full virtual register which is still live after the partial dead def.

This fixes PR14079.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165877 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-13 17:26:47 +00:00
Jakob Stoklund Olesen
af89690760 Allow for loops in LiveIntervals::pruneValue().
It is possible that the live range of the value being pruned loops back
into the kill MBB where the search started. When that happens, make sure
that the beginning of KillMBB is also pruned.

Instead of starting a DFS at KillMBB and skipping the root of the
search, start a DFS at each KillMBB successor, and allow the search to
loop back to KillMBB.

This fixes PR14078.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165872 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-13 16:15:31 +00:00
Benjamin Kramer
f8b65aaf39 X86: Fix accidentally swapped operands.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165871 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-13 12:50:19 +00:00
Benjamin Kramer
444dccecfc X86: Promote i8 cmov when both operands are coming from truncates of the same width.
X86 doesn't have i8 cmovs so isel would emit a branch. Emitting branches at this
level is often not a good idea because it's too late for many optimizations to
kick in. This solution doesn't add any extensions (truncs are free) and tries
to avoid introducing partial register stalls by filtering direct copyfromregs.

I'm seeing a ~10% speedup on reading a random .png file with libpng15 via
graphicsmagick on x86_64/westmere, but YMMV depending on the microarchitecture.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165868 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-13 10:39:49 +00:00
Manman Ren
e6c3cc8dc5 ARM: tail-call inside a function where part of a byval argument is on caller's
local frame causes problem.

For example:
void f(StructToPass s) {
  g(&s, sizeof(s));
}
will cause problem with tail-call since part of s is passed via registers and
saved in f's local frame. When g tries to access s, part of s may be corrupted
since f's local frame is popped out before the tail-call.

The current fix is to disable tail-call if getVarArgsRegSaveSize is not 0 for
the caller. This is a conservative approach, if we can prove the address of
s or part of s is not taken and passed to g, it should be okay to perform
tail-call.

rdar://12442472


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165853 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-12 23:39:43 +00:00
Jakob Stoklund Olesen
2bbb07d13c Fix buildbots: -misched=shuffle is only available in +Asserts builds.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165846 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-12 23:01:33 +00:00
Jim Grosbach
4346fa9437 ARM: Mark VSELECT as 'expand'.
The backend already pattern matches to form VBSL when it can. We may want to
teach it to use the vbsl intrinsics at some point to prevent machine licm from
mucking with this, but using the Expand is completely correct.

http://llvm.org/bugs/show_bug.cgi?id=13831
http://llvm.org/bugs/show_bug.cgi?id=13961

Patch by Peter Couperus <peter.couperus@st.com>.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165845 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-12 22:59:21 +00:00
Jakob Stoklund Olesen
ad5e969ba9 Use a transposed algorithm for handleMove().
Completely update one interval at a time instead of collecting live
range fragments to be updated. This avoids building data structures,
except for a single SmallPtrSet of updated intervals.

Also share code between handleMove() and handleMoveIntoBundle().

Add support for moving dead defs across other live values in the
interval. The MI scheduler can do that.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165824 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-12 21:31:57 +00:00
Jakob Stoklund Olesen
795f951c6d Fix coalescing with IMPLICIT_DEF values.
PHIElimination inserts IMPLICIT_DEF instructions to guarantee that all
PHI predecessors have a live-out value. These IMPLICIT_DEF values are
not considered to be real interference when coalescing virtual
registers:

  %vreg1 = IMPLICIT_DEF
  %vreg2 = MOV32r0

When joining %vreg1 and %vreg2, the IMPLICIT_DEF instruction and its
value number should simply be erased since the %vreg2 value number now
provides a live-out value for the PHI predecesor block.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165813 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-12 18:03:04 +00:00