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Fix PR15332 (patch by Florian Zeitz).

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There's no need to generate a stack frame for PPC32 SVR4 when there are
no local variables assigned to the stack, i.e., when no red zone is needed.
(PPC64 supports a red zone, but PPC32 does not.)

llvm-svn: 176124
This commit is contained in:
Bill Schmidt 2013-02-26 21:28:57 +00:00
parent 13a0226aef
commit 5440b8eaca
2 changed files with 44 additions and 4 deletions
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9
lib/Target/PowerPC/PPCFrameLowering.cpp
View File

@ -207,13 +207,14 @@ void PPCFrameLowering::determineFrameLayout(MachineFunction &MF) const {
// to adjust the stack pointer (we fit in the Red Zone). For 64-bit
// SVR4, we also require a stack frame if we need to spill the CR,
// since this spill area is addressed relative to the stack pointer.
// The 32-bit SVR4 ABI has no Red Zone. However, it can still generate
// stackless code if all local vars are reg-allocated.
bool DisableRedZone = MF.getFunction()->getAttributes().
hasAttribute(AttributeSet::FunctionIndex, Attribute::NoRedZone);
// FIXME SVR4 The 32-bit SVR4 ABI has no red zone. However, it can
// still generate stackless code if all local vars are reg-allocated.
// Try: (FrameSize <= 224
// || (FrameSize == 0 && Subtarget.isPPC32 && Subtarget.isSVR4ABI()))
if (!DisableRedZone &&
(Subtarget.isPPC64() || // 32-bit SVR4, no stack-
!Subtarget.isSVR4ABI() || // allocated locals.
FrameSize == 0) &&
FrameSize <= 224 && // Fits in red zone.
!MFI->hasVarSizedObjects() && // No dynamic alloca.
!MFI->adjustsStack() && // No calls.

39
test/CodeGen/PowerPC/svr4-redzone.ll Normal file
View File

@ -0,0 +1,39 @@
; RUN: llc -mtriple="powerpc-unknown-linux-gnu" < %s | FileCheck %s --check-prefix=PPC32
; RUN: llc -mtriple="powerpc64-unknown-linux-gnu" < %s | FileCheck %s --check-prefix=PPC64
; PR15332
define void @regalloc() nounwind {
entry:
%0 = add i32 1, 2
ret void
}
; PPC32: regalloc:
; PPC32-NOT: stwu 1, -{{[0-9]+}}(1)
; PPC32: blr
; PPC64: regalloc:
; PPC64-NOT: stdu 1, -{{[0-9]+}}(1)
; PPC64: blr
define void @smallstack() nounwind {
entry:
%0 = alloca i8, i32 4
ret void
}
; PPC32: smallstack:
; PPC32: stwu 1, -16(1)
; PPC64: smallstack:
; PPC64-NOT: stdu 1, -{{[0-9]+}}(1)
; PPC64: blr
define void @bigstack() nounwind {
entry:
%0 = alloca i8, i32 230
ret void
}
; PPC32: bigstack:
; PPC32: stwu 1, -240(1)
; PPC64: bigstack:
; PPC64: stdu 1, -352(1)