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Correctly handle <undef> tied uses when rewriting after a split.

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This fixes PR10463. A two-address instruction with an <undef> use
operand was incorrectly rewritten so the def and use no longer used the
same register, violating the tie constraint.

Fix this by always rewriting <undef> operands with the register a def
operand would use.

llvm-svn: 135885
This commit is contained in:
Jakob Stoklund Olesen 2011-07-24 20:23:50 +00:00
parent e238f52543
commit 0e4f7f92a2
2 changed files with 29 additions and 8 deletions
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12
lib/CodeGen/SplitKit.cpp
View File

@ -938,15 +938,11 @@ void SplitEditor::rewriteAssigned(bool ExtendRanges) {
continue;
}
// <undef> operands don't really read the register, so just assign them to
// the complement.
if (MO.isUse() && MO.isUndef()) {
MO.setReg(Edit->get(0)->reg);
continue;
}
// <undef> operands don't really read the register, so it doesn't matter
// which register we choose. When the use operand is tied to a def, we must
// use the same register as the def, so just do that always.
SlotIndex Idx = LIS.getInstructionIndex(MI);
if (MO.isDef())
if (MO.isDef() || MO.isUndef())
Idx = MO.isEarlyClobber() ? Idx.getUseIndex() : Idx.getDefIndex();
// Rewrite to the mapped register at Idx.

25
test/CodeGen/X86/crash.ll
View File

@ -316,3 +316,28 @@ declare void @_ZNSt6vectorIN4llvm11MachineMoveESaIS1_EE13_M_insert_auxEN9__gnu_c
declare void @llvm.lifetime.start(i64, i8* nocapture) nounwind
declare void @llvm.lifetime.end(i64, i8* nocapture) nounwind
; PR10463
; Spilling a virtual register with <undef> uses.
define void @autogen_239_1000() {
BB:
%Shuff = shufflevector <8 x double> undef, <8 x double> undef, <8 x i32> <i32 0, i32 2, i32 4, i32 6, i32 8, i32 10, i32 undef, i32 undef>
br label %CF
CF:
%B16 = frem <8 x double> zeroinitializer, %Shuff
%E19 = extractelement <8 x double> %Shuff, i32 5
br i1 undef, label %CF, label %CF75
CF75:
br i1 undef, label %CF75, label %CF76
CF76:
store double %E19, double* undef
br i1 undef, label %CF76, label %CF77
CF77:
%B55 = fmul <8 x double> %B16, undef
br label %CF77
}