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X86: Don't fold spills into SSE operations if the stack is unaligned.

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Regalloc can emit unaligned spills nowadays, but we can't fold the
spills into SSE ops if we can't guarantee alignment. PR12250.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192064 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Benjamin Kramer 2013-10-06 13:48:22 +00:00
parent 714319a169
commit d9f7a185e3
2 changed files with 53 additions and 0 deletions
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4
lib/Target/X86/X86InstrInfo.cpp
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@ -4166,6 +4166,10 @@ MachineInstr* X86InstrInfo::foldMemoryOperandImpl(MachineFunction &MF,
const MachineFrameInfo *MFI = MF.getFrameInfo();
unsigned Size = MFI->getObjectSize(FrameIndex);
unsigned Alignment = MFI->getObjectAlignment(FrameIndex);
// If the function stack isn't realigned we don't want to fold instructions
// that need increased alignment.
if (!RI.needsStackRealignment(MF))
Alignment = std::min(Alignment, TM.getFrameLowering()->getStackAlignment());
if (Ops.size() == 2 && Ops[0] == 0 && Ops[1] == 1) {
unsigned NewOpc = 0;
unsigned RCSize = 0;

49
test/CodeGen/X86/unaligned-spill-folding.ll Normal file
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@ -0,0 +1,49 @@
; RUN: llc -mtriple=i386-unknown-freebsd -mattr=sse2 -stack-alignment=4 -relocation-model=pic < %s | FileCheck %s -check-prefix=UNALIGNED
; RUN: llc -mtriple=i386-unknown-freebsd -mattr=sse2 -stack-alignment=16 -relocation-model=pic < %s | FileCheck %s -check-prefix=ALIGNED
; RUN: llc -mtriple=i386-unknown-freebsd -mattr=sse2 -stack-alignment=4 -force-align-stack -relocation-model=pic < %s | FileCheck %s -check-prefix=FORCEALIGNED
@arr = internal unnamed_addr global [32 x i32] zeroinitializer, align 16
; PR12250
define i32 @test1() {
vector.ph:
br label %vector.body
vector.body:
%index = phi i32 [ 0, %vector.ph ], [ %index.next, %vector.body ]
%0 = getelementptr inbounds [32 x i32]* @arr, i32 0, i32 %index
%1 = bitcast i32* %0 to <4 x i32>*
%wide.load = load <4 x i32>* %1, align 16
%2 = add nsw <4 x i32> %wide.load, <i32 10, i32 10, i32 10, i32 10>
%3 = xor <4 x i32> %2, <i32 123345, i32 123345, i32 123345, i32 123345>
%4 = add nsw <4 x i32> %3, <i32 112, i32 112, i32 112, i32 112>
%5 = xor <4 x i32> %4, <i32 543345, i32 543345, i32 543345, i32 543345>
%6 = add nsw <4 x i32> %5, <i32 73, i32 73, i32 73, i32 73>
%7 = xor <4 x i32> %6, <i32 345987, i32 345987, i32 345987, i32 345987>
%8 = add nsw <4 x i32> %7, <i32 48, i32 48, i32 48, i32 48>
%9 = xor <4 x i32> %8, <i32 123987, i32 123987, i32 123987, i32 123987>
store <4 x i32> %9, <4 x i32>* %1, align 16
%index.next = add i32 %index, 4
%10 = icmp eq i32 %index.next, 32
br i1 %10, label %middle.block, label %vector.body
middle.block:
ret i32 0
; We can't fold the spill into a padd unless the stack is aligned. Just spilling
; doesn't force stack realignment though
; UNALIGNED-LABEL: @test1
; UNALIGNED-NOT: andl $-{{..}}, %esp
; UNALIGNED: movdqu {{.*}} # 16-byte Folded Spill
; UNALIGNED-NOT: paddd {{.*}} # 16-byte Folded Reload
; ALIGNED-LABEL: @test1
; ALIGNED-NOT: andl $-{{..}}, %esp
; ALIGNED: movdqa {{.*}} # 16-byte Spill
; ALIGNED: paddd {{.*}} # 16-byte Folded Reload
; FORCEALIGNED-LABEL: @test1
; FORCEALIGNED: andl $-{{..}}, %esp
; FORCEALIGNED: movdqa {{.*}} # 16-byte Spill
; FORCEALIGNED: paddd {{.*}} # 16-byte Folded Reload
}