449 Commits

Author SHA1 Message Date
Simon Pilgrim
0d1978b813 [X86] Memory folding for commutative instructions (updated)
This patch improves support for commutative instructions in the x86 memory folding implementation by attempting to fold a commuted version of the instruction if the original folding fails - if that folding fails as well the instruction is 're-commuted' back to its original order before returning.

Updated version of r219584 (reverted in r219595) - the commutation attempt now explicitly ensures that neither of the commuted source operands are tied to the destination operand / register, which was the source of all the regressions that occurred with the original patch attempt.

Added additional regression test case provided by Joerg Sonnenberger.

Differential Revision: http://reviews.llvm.org/D5818



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220239 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-20 22:14:22 +00:00
NAKAMURA Takumi
58c0f65bf2 Revert r219584, "[X86] Memory folding for commutative instructions."
It broke i686 selfhosting.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219595 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-13 04:17:34 +00:00
Simon Pilgrim
c00cd8e3c8 [X86] Memory folding for commutative instructions.
This patch improves support for commutative instructions in the x86 memory folding implementation by attempting to fold a commuted version of the instruction if the original folding fails - if that folding fails as well the instruction is 're-commuted' back to its original order before returning.

This mainly helps the stack inliner better fold reloads of 3 (or more) operand instructions (VEX encoded SSE etc.) but by performing this in the lowest foldMemoryOperandImpl implementation it also replaces the X86InstrInfo::optimizeLoadInstr version and is now used by FastISel too.

Differential Revision: http://reviews.llvm.org/D5701


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219584 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-12 10:52:55 +00:00
Adrian Prantl
02474a32eb Move the complex address expression out of DIVariable and into an extra
argument of the llvm.dbg.declare/llvm.dbg.value intrinsics.

Previously, DIVariable was a variable-length field that has an optional
reference to a Metadata array consisting of a variable number of
complex address expressions. In the case of OpPiece expressions this is
wasting a lot of storage in IR, because when an aggregate type is, e.g.,
SROA'd into all of its n individual members, the IR will contain n copies
of the DIVariable, all alike, only differing in the complex address
reference at the end.

By making the complex address into an extra argument of the
dbg.value/dbg.declare intrinsics, all of the pieces can reference the
same variable and the complex address expressions can be uniqued across
the CU, too.
Down the road, this will allow us to move other flags, such as
"indirection" out of the DIVariable, too.

The new intrinsics look like this:
declare void @llvm.dbg.declare(metadata %storage, metadata %var, metadata %expr)
declare void @llvm.dbg.value(metadata %storage, i64 %offset, metadata %var, metadata %expr)

This patch adds a new LLVM-local tag to DIExpressions, so we can detect
and pretty-print DIExpression metadata nodes.

What this patch doesn't do:

This patch does not touch the "Indirect" field in DIVariable; but moving
that into the expression would be a natural next step.

http://reviews.llvm.org/D4919
rdar://problem/17994491

Thanks to dblaikie and dexonsmith for reviewing this patch!

Note: I accidentally committed a bogus older version of this patch previously.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218787 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-01 18:55:02 +00:00
Adrian Prantl
10c4265675 Revert r218778 while investigating buldbot breakage.
"Move the complex address expression out of DIVariable and into an extra"

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218782 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-01 18:10:54 +00:00
Adrian Prantl
076fd5dfc1 Move the complex address expression out of DIVariable and into an extra
argument of the llvm.dbg.declare/llvm.dbg.value intrinsics.

Previously, DIVariable was a variable-length field that has an optional
reference to a Metadata array consisting of a variable number of
complex address expressions. In the case of OpPiece expressions this is
wasting a lot of storage in IR, because when an aggregate type is, e.g.,
SROA'd into all of its n individual members, the IR will contain n copies
of the DIVariable, all alike, only differing in the complex address
reference at the end.

By making the complex address into an extra argument of the
dbg.value/dbg.declare intrinsics, all of the pieces can reference the
same variable and the complex address expressions can be uniqued across
the CU, too.
Down the road, this will allow us to move other flags, such as
"indirection" out of the DIVariable, too.

The new intrinsics look like this:
declare void @llvm.dbg.declare(metadata %storage, metadata %var, metadata %expr)
declare void @llvm.dbg.value(metadata %storage, i64 %offset, metadata %var, metadata %expr)

This patch adds a new LLVM-local tag to DIExpressions, so we can detect
and pretty-print DIExpression metadata nodes.

What this patch doesn't do:

This patch does not touch the "Indirect" field in DIVariable; but moving
that into the expression would be a natural next step.

http://reviews.llvm.org/D4919
rdar://problem/17994491

Thanks to dblaikie and dexonsmith for reviewing this patch!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218778 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-01 17:55:39 +00:00
Daniel Sanders
1d545d9acb Add llvm_unreachables() for [ASZ]ExtUpper to X86FastISel.cpp to appease the buildbots.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218452 91177308-0d34-0410-b5e6-96231b3b80d8
2014-09-25 13:08:51 +00:00
Juergen Ributzka
1ee1e8bdc2 [FastISel] Move optimizeCmpPredicate to FastISel base class. NFC.
Make the optimizeCmpPredicate function available to all targets.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217822 91177308-0d34-0410-b5e6-96231b3b80d8
2014-09-15 20:47:13 +00:00
Juergen Ributzka
ecadea992a [FastISel][tblgen] Rename tblgen generated FastISel functions. NFC.
This is the final round of renaming. This changes tblgen to emit lower-case
function names for FastEmitInst_* and FastEmit_*, and updates all its uses
in the source code.

Reviewed by Eric

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217075 91177308-0d34-0410-b5e6-96231b3b80d8
2014-09-03 20:56:59 +00:00
Juergen Ributzka
6042034603 [FastISel] Rename public visible FastISel functions. NFC.
This commit renames the following public FastISel functions:
LowerArguments -> lowerArguments
SelectInstruction -> selectInstruction
TargetSelectInstruction -> fastSelectInstruction
FastLowerArguments -> fastLowerArguments
FastLowerCall -> fastLowerCall
FastLowerIntrinsicCall -> fastLowerIntrinsicCall
FastEmitZExtFromI1 -> fastEmitZExtFromI1
FastEmitBranch -> fastEmitBranch
UpdateValueMap -> updateValueMap
TargetMaterializeConstant -> fastMaterializeConstant
TargetMaterializeAlloca -> fastMaterializeAlloca
TargetMaterializeFloatZero -> fastMaterializeFloatZero
LowerCallTo -> lowerCallTo

Reviewed by Eric

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217074 91177308-0d34-0410-b5e6-96231b3b80d8
2014-09-03 20:56:52 +00:00
Juergen Ributzka
96b1e70c66 Reapply [FastISel][X86] Add large code model support for materializing floating-point constants (r215595).
Note: This was originally reverted to track down a buildbot error. Reapply
without any modifications.

Original commit message:
In the large code model for X86 floating-point constants are placed in the
constant pool and materialized by loading from it. Since the constant pool
could be far away, a PC relative load might not work. Therefore we first
materialize the address of the constant pool with a movabsq and then load
from there the floating-point value.

Fixes <rdar://problem/17674628>.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216012 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-19 19:44:13 +00:00
Juergen Ributzka
9c23685dd2 Reapply [FastISel][X86] Use XOR to materialize the "0" value (r215594).
Note: This was originally reverted to track down a buildbot error. Reapply
without any modifications.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216011 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-19 19:44:10 +00:00
Juergen Ributzka
e8757c5dbb Reapply [FastISel][X86] Emit more efficient instructions for integer constant materialization (r215593).
Note: This was originally reverted to track down a buildbot error. Reapply
without any modifications.

Original commit message:
This mostly affects the i64 value type, which always resulted in an 15byte
mobavsq instruction to materialize any constant. The custom code checks the
value of the immediate and tries to use a different and smaller mov
instruction when possible.

This fixes <rdar://problem/17420988>.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216010 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-19 19:44:06 +00:00
Juergen Ributzka
6398a7f5fd Revert several FastISel commits to track down a buildbot error.
This reverts:
r215595 "[FastISel][X86] Add large code model support for materializing floating-point constants."
r215594 "[FastISel][X86] Use XOR to materialize the "0" value."
r215593 "[FastISel][X86] Emit more efficient instructions for integer constant materialization."
r215591 "[FastISel][AArch64] Make use of the zero register when possible."
r215588 "[FastISel] Let the target decide first if it wants to materialize a constant."
r215582 "[FastISel][AArch64] Cleanup constant materialization code. NFCI."

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215673 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-14 19:56:28 +00:00
Juergen Ributzka
b677a877c8 [FastISel][X86] Add large code model support for materializing floating-point constants.
In the large code model for X86 floating-point constants are placed in the
constant pool and materialized by loading from it. Since the constant pool
could be far away, a PC relative load might not work. Therefore we first
materialize the address of the constant pool with a movabsq and then load
from there the floating-point value.

Fixes <rdar://problem/17674628>.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215595 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-13 22:25:35 +00:00
Juergen Ributzka
0701e5d43b [FastISel][X86] Use XOR to materialize the "0" value.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215594 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-13 22:22:17 +00:00
Juergen Ributzka
f245d9aa77 [FastISel][X86] Emit more efficient instructions for integer constant materialization.
This mostly affects the i64 value type, which always resulted in an 15byte
mobavsq instruction to materialize any constant. The custom code checks the
value of the immediate and tries to use a different and smaller mov
instruction when possible.

This fixes <rdar://problem/17420988>.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215593 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-13 22:18:11 +00:00
Juergen Ributzka
a0c81f0639 [FastISel][X86] Refactor constant materialization. NFCI.
Split the constant materialization code into three separate helper functions for
Integer-, Floating-Point-, and GlobalValue-Constants.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215586 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-13 22:01:55 +00:00
Rui Ueyama
72260fe2b4 [FastISel][X86] Silence -Wenum-compare warning
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215253 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-08 22:47:49 +00:00
Juergen Ributzka
0980ef248e [FastISel][X86] Fix INC/DEC optimization (r215230)
I accidentally also used INC/DEC for unsigned arithmetic which doesn't work,
because INC/DEC don't set the required flag which is used for the overflow
check.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215237 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-08 18:47:04 +00:00
Juergen Ributzka
cbda4b32c6 [FastISel][X86] Use INC/DEC when possible for {sadd|ssub}.with.overflow intrinsics.
This is a small peephole optimization to emit INC/DEC when possible.

Fixes <rdar://problem/17952308>.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215230 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-08 17:21:37 +00:00
Eric Christopher
41612a9b85 Remove the target machine from CCState. Previously it was only used
to get the subtarget and that's accessible from the MachineFunction
now. This helps clear the way for smaller changes where we getting
a subtarget will require passing in a MachineFunction/Function as
well.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214988 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-06 18:45:26 +00:00
Eric Christopher
9f85dccfc6 Remove the TargetMachine forwards for TargetSubtargetInfo based
information and update all callers. No functional change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214781 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-04 21:25:23 +00:00
Akira Hatanaka
306030f8aa [X86] Simplify X87 stackifier pass.
Stop using ST registers for function returns and inline-asm instructions and use
FP registers instead. This allows removing a large amount of code in the
stackifier pass that was needed to track register liveness and handle copies
between ST and FP registers and function calls returning floating point values.

It also fixes a bug which manifests when an ST register defined by an
inline-asm instruction was live across another inline-asm instruction, as shown
in the following sequence of machine instructions:

1. INLINEASM <es:frndint> $0:[regdef], %ST0<imp-def,tied5>
2. INLINEASM <es:fldcw $0>
3. %FP0<def> = COPY %ST0

<rdar://problem/16952634>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214580 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-01 22:19:41 +00:00
Juergen Ributzka
450c33b212 [FastISel][AArch64 and X86] Don't emit stores for UNDEF arguments during function call lowering.
UNDEF arguments are not ment to be touched - especially for the webkit_js
calling convention. This fix reproduces the already existing behavior of
SelectionDAG in FastISel.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214366 91177308-0d34-0410-b5e6-96231b3b80d8
2014-07-31 00:11:11 +00:00
Juergen Ributzka
07731b34fb [FastISel] Move the helper function isCommutativeIntrinsic into FastISel base class.
Move the helper function isCommutativeIntrinsic into the FastISel base class,
so it can be used by more than just one backend.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214347 91177308-0d34-0410-b5e6-96231b3b80d8
2014-07-30 22:04:28 +00:00
Andrea Di Biagio
a34d957b61 Silence a warning in conditional expression.
Fixes a gcc warning caused by a typo. A redundant assignment operation was
accidentally used as the third operand of a conditional expression.
No functional change intended.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213061 91177308-0d34-0410-b5e6-96231b3b80d8
2014-07-15 10:53:44 +00:00
Juergen Ributzka
cce1bd7a0b [FastISel][X86] Remove no longer needed functions.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213051 91177308-0d34-0410-b5e6-96231b3b80d8
2014-07-15 06:35:53 +00:00
Juergen Ributzka
1b0266d7cb [FastISel][X86] Implement the FastLowerIntrinsicCall hook.
Rename X86VisitIntrinsicCall -> FastLowerIntrinsicCall, which effectively
implements the target hook.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213050 91177308-0d34-0410-b5e6-96231b3b80d8
2014-07-15 06:35:50 +00:00
Juergen Ributzka
566afe2a15 [FastISel][X86] Implement the FastLowerCall hook.
This implements the FastLowerCall hook, which is based on the DoSelectCall
function. The implementation is very similar, but the target-independent call
lowering part has been factored out.

This should also enable patchpoint intrinsic lowering for FastISel on X86.

Related to <rdar://problem/17427052>.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213049 91177308-0d34-0410-b5e6-96231b3b80d8
2014-07-15 06:35:47 +00:00
Juergen Ributzka
a107ebd54d Revert "[FastISel][X86] Remove no longer needed functions."
Revert "[FastISel][X86] Implement the FastLowerIntrinsicCall hook."
Revert "[FastISel][X86] Implement the FastLowerCall hook."

This reverts commit r213035, r213036, and r213037 to make the
buildbots happy again.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213048 91177308-0d34-0410-b5e6-96231b3b80d8
2014-07-15 05:23:40 +00:00
Juergen Ributzka
3c0737454d [FastISel][X86] Remove no longer needed functions.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213037 91177308-0d34-0410-b5e6-96231b3b80d8
2014-07-15 02:22:56 +00:00
Juergen Ributzka
a7d1d3a513 [FastISel][X86] Implement the FastLowerIntrinsicCall hook.
Rename X86VisitIntrinsicCall -> FastLowerIntrinsicCall, which effectively
implements the target hook.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213036 91177308-0d34-0410-b5e6-96231b3b80d8
2014-07-15 02:22:53 +00:00
Juergen Ributzka
805486c3f9 [FastISel][X86] Implement the FastLowerCall hook.
This implements the FastLowerCall hook, which is based on the DoSelectCall
function. The implementation is very similar, but the target-independent call
lowering part has been factored out.

This should also enable patchpoint intrinsic lowering for FastISel on X86.

Related to <rdar://problem/17427052>.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213035 91177308-0d34-0410-b5e6-96231b3b80d8
2014-07-15 02:22:49 +00:00
Juergen Ributzka
b2e9db4109 Revert "[FastISel][X86] Implement the FastLowerIntrinsicCall hook."
This reverts commit r212851, because it broke the memset lowering.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212855 91177308-0d34-0410-b5e6-96231b3b80d8
2014-07-11 23:10:08 +00:00
Juergen Ributzka
83772afe0e [FastISel][X86] Implement the FastLowerIntrinsicCall hook.
Rename X86VisitIntrinsicCall -> FastLowerIntrinsicCall, which effectively
implements the target hook.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212851 91177308-0d34-0410-b5e6-96231b3b80d8
2014-07-11 22:37:43 +00:00
Juergen Ributzka
1154be8198 [FastISel][X86] Fix smul.with.overflow.i8 lowering.
Add custom lowering code for signed multiply instruction selection, because the
default FastISel instruction selection for ISD::MUL will use unsigned multiply
for the i8 type and signed multiply for all other types. This would set the
incorrect flags for the overflow check.

This fixes <rdar://problem/17549300>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212493 91177308-0d34-0410-b5e6-96231b3b80d8
2014-07-07 21:52:21 +00:00
Tim Northover
a15d70370e X86: revert unintentional change to X86FastISel.
This crept in with r212443.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212459 91177308-0d34-0410-b5e6-96231b3b80d8
2014-07-07 14:06:42 +00:00
Tim Northover
3e16b022be CodeGen: it turns out that NAND is not the same thing as BIC. At all.
We've been performing the wrong operation on ARM for "atomicrmw nand" for
years, since "a NAND b" is "~(a & b)" rather than ARM's very tempting "a & ~b".
This bled over into the generic expansion pass.

So I assume no-one has ever actually tried to do an atomic nand in the real
world. Oh well.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212443 91177308-0d34-0410-b5e6-96231b3b80d8
2014-07-07 09:06:35 +00:00
Saleem Abdulrasool
2c25d41c21 X86: fix comment
Fix a comment typo `DbgLocLImport` instead of `DLLImport`.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212012 91177308-0d34-0410-b5e6-96231b3b80d8
2014-06-30 03:11:18 +00:00
Juergen Ributzka
6d557f37cf [FastISel][X86] Fix typos.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211911 91177308-0d34-0410-b5e6-96231b3b80d8
2014-06-27 17:16:34 +00:00
Craig Topper
ba39a59cd0 Rename getX86ConditonCode -> getX86ConditionCode
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211869 91177308-0d34-0410-b5e6-96231b3b80d8
2014-06-27 05:18:21 +00:00
Juergen Ributzka
0956faba3d [FastISel][X86] More refactoring of select lowering and XALU folding. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211740 91177308-0d34-0410-b5e6-96231b3b80d8
2014-06-25 22:50:59 +00:00
Juergen Ributzka
a98f7c7720 [FastISel][X86] Refactor XALU folding. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211735 91177308-0d34-0410-b5e6-96231b3b80d8
2014-06-25 22:17:23 +00:00
Juergen Ributzka
d01f1c4054 [FastISel][X86] Only fold the cmp into the select when both instructions are in the same basic block.
If the cmp is in a different basic block, then it is possible that not all
operands of that compare have defined registers. This can happen when one of
the operands to the cmp is a load and the load gets folded into the cmp. In
this case FastISel will skip the load instruction and the vreg is never
defined.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211730 91177308-0d34-0410-b5e6-96231b3b80d8
2014-06-25 20:06:12 +00:00
Juergen Ributzka
75f1d664b4 Fix indentation.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211717 91177308-0d34-0410-b5e6-96231b3b80d8
2014-06-25 16:49:37 +00:00
Juergen Ributzka
35a6a81407 [FastISel][X86] Fold XALU condition into branch and compare.
Optimize the codegen of select and branch instructions to directly use the
EFLAGS from the {s|u}{add|sub|mul}.with.overflow intrinsics.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211645 91177308-0d34-0410-b5e6-96231b3b80d8
2014-06-24 23:51:21 +00:00
Juergen Ributzka
20732d55c2 [FastISel][X86] Lower unsupported selects to control-flow.
The extends the select lowering coverage by emiting pseudo cmov
instructions. These insturction will be later on lowered to control-flow to
simulate the select.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211545 91177308-0d34-0410-b5e6-96231b3b80d8
2014-06-23 21:55:44 +00:00
Juergen Ributzka
d0976a3d20 [FastISel][X86] Add support for floating-point select.
This extends the select lowering to support floating-point selects. The
lowering depends on SSE instructions and that the conditon comes from a
floating-point compare. Under this conditions it is possible to emit an
optimized instruction sequence that doesn't require any branches to
simulate the select.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211544 91177308-0d34-0410-b5e6-96231b3b80d8
2014-06-23 21:55:40 +00:00
Juergen Ributzka
5f4e6e1ec0 [FastISel][X86] Optimize selects when the condition comes from a compare.
Optimize the select instructions sequence to use the EFLAGS directly from a
compare when possible.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211543 91177308-0d34-0410-b5e6-96231b3b80d8
2014-06-23 21:55:36 +00:00