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author | Tim Northover <tnorthover@apple.com> | 2013-12-09 09:05:30 +0000 |
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committer | Tim Northover <tnorthover@apple.com> | 2013-12-09 09:05:30 +0000 |
commit | 54ed08e250a76b570c2162d49633e11b8ebb2d98 (patch) | |
tree | 7391ecf1a422133317d0242a99306f576ad03870 | |
parent | 7d9c02dc620ea5f5cdf2dc0bd0f03d9370f845d3 (diff) | |
download | llvm-54ed08e250a76b570c2162d49633e11b8ebb2d98.tar.gz llvm-54ed08e250a76b570c2162d49633e11b8ebb2d98.tar.bz2 llvm-54ed08e250a76b570c2162d49633e11b8ebb2d98.tar.xz |
Merge r196725 (conflicts on same API as before):
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r196725 | tnorthover | 2013-12-08 15:56:50 +0000 (Sun, 08 Dec 2013) |
19 lines
ARM: fix folding of stack-adjustment (yet again).
When trying to eliminate an "sub sp, sp, #N" instruction by folding
it into an existing push/pop using dummy registers, we need to account
for the fact that this might affect precisely how "fp" gets set in the
prologue.
We were attempting this, but assuming that *whenever* we performed a
fold it would make a difference. This is false, for example, in:
push {r4, r7, lr}
add fp, sp, #4
vpush {d8}
sub sp, sp, #8
we can fold the "sub" into the "vpush", forming "vpush {d7, d8}".
However, in that case the "add fp" instruction mustn't change, which
we were getting wrong before.
Should fix PR18160.
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_34@196769 91177308-0d34-0410-b5e6-96231b3b80d8
-rw-r--r-- | lib/Target/ARM/ARMFrameLowering.cpp | 7 | ||||
-rw-r--r-- | test/CodeGen/ARM/fold-stack-adjust.ll | 9 |
2 files changed, 13 insertions, 3 deletions
diff --git a/lib/Target/ARM/ARMFrameLowering.cpp b/lib/Target/ARM/ARMFrameLowering.cpp index 1457ace6bc..d32bdbc589 100644 --- a/lib/Target/ARM/ARMFrameLowering.cpp +++ b/lib/Target/ARM/ARMFrameLowering.cpp @@ -256,9 +256,10 @@ void ARMFrameLowering::emitPrologue(MachineFunction &MF) const { if (NumBytes) { // Adjust SP after all the callee-save spills. - if (tryFoldSPUpdateIntoPushPop(MF, LastPush, NumBytes)) - FramePtrOffsetInPush += NumBytes; - else + if (tryFoldSPUpdateIntoPushPop(MF, LastPush, NumBytes)) { + if (LastPush == FramePtrPush) + FramePtrOffsetInPush += NumBytes; + } else emitSPUpdate(isARM, MBB, MBBI, dl, TII, -NumBytes, MachineInstr::FrameSetup); diff --git a/test/CodeGen/ARM/fold-stack-adjust.ll b/test/CodeGen/ARM/fold-stack-adjust.ll index 8c60bca1db..67fd129fd1 100644 --- a/test/CodeGen/ARM/fold-stack-adjust.ll +++ b/test/CodeGen/ARM/fold-stack-adjust.ll @@ -137,6 +137,15 @@ define void @test_fold_point(i1 %tst) minsize { ; CHECK: {{LBB[0-9]+_2}}: ; CHECK-NEXT: vpop {d7, d8} ; CHECK-NEXT: pop {r4, pc} + + ; With a guaranteed frame-pointer, we want to make sure that its offset in the + ; push block is correct, even if a few registers have been tacked onto a later + ; vpush (PR18160). +; CHECK-IOS-LABEL: test_fold_point: +; CHECK-IOS: push {r4, r7, lr} +; CHECK-IOS-NEXT: add r7, sp, #4 +; CHECK-IOS-NEXT: vpush {d7, d8} + ; We want some memory so there's a stack adjustment to fold... %var = alloca i8, i32 8 |