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Fix a bug in the local allocator's liveness computation where it

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was setting kill flags on tied uses in two-address instructions.
The kill flags were causing the allocator to think it could
allocate the use and its tied def in different registers.

llvm-svn: 57039
This commit is contained in:
Dan Gohman 2008-10-04 00:31:14 +00:00
parent dc83b95ba5
commit 638a8001c8
2 changed files with 36 additions and 3 deletions
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8
lib/CodeGen/RegAllocLocal.cpp
View File

@ -651,9 +651,11 @@ void RALocal::ComputeLocalLiveness(MachineBasicBlock& MBB) {
// Physical registers and those that are not live-out of the block
// are killed/dead at their last use/def within this block.
if (isPhysReg || !usedOutsideBlock) {
if (MO.isUse())
MO.setIsKill(true);
else
if (MO.isUse()) {
// Don't mark uses that are tied to defs as kills.
if (MI->getDesc().getOperandConstraint(idx, TOI::TIED_TO) == -1)
MO.setIsKill(true);
} else
MO.setIsDead(true);
}
}

31
test/CodeGen/X86/local-liveness.ll Normal file
View File

@ -0,0 +1,31 @@
; RUN: llvm-as < %s | llc -march=x86 -regalloc=local | grep {subl %eax, %esi}
; Local regalloc shouldn't assume that both the uses of the
; sub instruction are kills, because one of them is tied
; to an output. Previously, it was allocating both inputs
; in the same register.
define i32 @func_3() nounwind {
entry:
%retval = alloca i32 ; <i32*> [#uses=2]
%g_323 = alloca i8 ; <i8*> [#uses=2]
%p_5 = alloca i64, align 8 ; <i64*> [#uses=2]
%0 = alloca i32 ; <i32*> [#uses=2]
%"alloca point" = bitcast i32 0 to i32 ; <i32> [#uses=0]
store i64 0, i64* %p_5, align 8
store i8 1, i8* %g_323, align 1
%1 = load i8* %g_323, align 1 ; <i8> [#uses=1]
%2 = sext i8 %1 to i64 ; <i64> [#uses=1]
%3 = load i64* %p_5, align 8 ; <i64> [#uses=1]
%4 = sub i64 %3, %2 ; <i64> [#uses=1]
%5 = icmp sge i64 %4, 0 ; <i1> [#uses=1]
%6 = zext i1 %5 to i32 ; <i32> [#uses=1]
store i32 %6, i32* %0, align 4
%7 = load i32* %0, align 4 ; <i32> [#uses=1]
store i32 %7, i32* %retval, align 4
br label %return
return: ; preds = %entry
%retval1 = load i32* %retval ; <i32> [#uses=1]
ret i32 %retval1
}