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ARM / x86_64 varargs: Don't save regparms in prologue without va_start

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There's no need to do this if the user doesn't call va_start. In the
future, we're going to have thunks that forward these register
parameters with musttail calls, and they won't need these spills for
handling va_start.

Most of the test suite changes are adding va_start calls to existing
tests to keep things working.

llvm-svn: 216294
This commit is contained in:
Reid Kleckner 2014-08-22 21:59:26 +00:00
parent 78ec7d3e35
commit 60c1740ad6
12 changed files with 61 additions and 7 deletions
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8
include/llvm/CodeGen/MachineFrameInfo.h
View File

@ -236,6 +236,9 @@ class MachineFrameInfo {
/// pointer.
bool HasInlineAsmWithSPAdjust;
/// True if the function contains a call to the llvm.vastart intrinsic.
bool HasVAStart;
const TargetFrameLowering *getFrameLowering() const;
public:
explicit MachineFrameInfo(const TargetMachine &TM, bool RealignOpt)
@ -256,6 +259,7 @@ public:
LocalFrameMaxAlign = 0;
UseLocalStackAllocationBlock = false;
HasInlineAsmWithSPAdjust = false;
HasVAStart = false;
}
/// hasStackObjects - Return true if there are any stack objects in this
@ -475,6 +479,10 @@ public:
bool hasInlineAsmWithSPAdjust() const { return HasInlineAsmWithSPAdjust; }
void setHasInlineAsmWithSPAdjust(bool B) { HasInlineAsmWithSPAdjust = B; }
/// Returns true if the function calls the llvm.va_start intrinsic.
bool hasVAStart() const { return HasVAStart; }
void setHasVAStart(bool B) { HasVAStart = B; }
/// getMaxCallFrameSize - Return the maximum size of a call frame that must be
/// allocated for an outgoing function call. This is only available if
/// CallFrameSetup/Destroy pseudo instructions are used by the target, and

8
lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
View File

@ -138,6 +138,14 @@ void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf,
}
}
// Look for calls to the @llvm.va_start intrinsic. We can omit some
// prologue boilerplate for variadic functions that don't examine their
// arguments.
if (const auto *II = dyn_cast<IntrinsicInst>(I)) {
if (II->getIntrinsicID() == Intrinsic::vastart)
MF->getFrameInfo()->setHasVAStart(true);
}
// Mark values used outside their block as exported, by allocating
// a virtual register for them.
if (isUsedOutsideOfDefiningBlock(I))

4
lib/Target/ARM/ARMISelLowering.cpp
View File

@ -3080,7 +3080,7 @@ ARMTargetLowering::LowerFormalArguments(SDValue Chain,
}
CCInfo.rewindByValRegsInfo();
lastInsIndex = -1;
if (isVarArg) {
if (isVarArg && MFI->hasVAStart()) {
unsigned ExtraArgRegsSize;
unsigned ExtraArgRegsSaveSize;
computeRegArea(CCInfo, MF, CCInfo.getInRegsParamsCount(), 0,
@ -3222,7 +3222,7 @@ ARMTargetLowering::LowerFormalArguments(SDValue Chain,
}
// varargs
if (isVarArg)
if (isVarArg && MFI->hasVAStart())
VarArgStyleRegisters(CCInfo, DAG, dl, Chain,
CCInfo.getNextStackOffset(),
TotalArgRegsSaveSize);

5
lib/Target/X86/X86ISelLowering.cpp
View File

@ -2405,8 +2405,9 @@ X86TargetLowering::LowerFormalArguments(SDValue Chain,
StackSize = GetAlignedArgumentStackSize(StackSize, DAG);
// If the function takes variable number of arguments, make a frame index for
// the start of the first vararg value... for expansion of llvm.va_start.
if (isVarArg) {
// the start of the first vararg value... for expansion of llvm.va_start. We
// can skip this if there are no va_start calls.
if (isVarArg && MFI->hasVAStart()) {
if (Is64Bit || (CallConv != CallingConv::X86_FastCall &&
CallConv != CallingConv::X86_ThisCall)) {
FuncInfo->setVarArgsFrameIndex(MFI->CreateFixedObject(1, StackSize,true));

3
test/CodeGen/ARM/fold-stack-adjust.ll
View File

@ -183,6 +183,7 @@ define void @test_varsize(...) minsize {
; CHECK: bx lr
%var = alloca i8, i32 8
call void @llvm.va_start(i8* %var)
call void @bar(i8* %var)
ret void
}
@ -216,3 +217,5 @@ if.then: ; preds = %entry
exit: ; preds = %if.then, %entry
ret float %call1
}
declare void @llvm.va_start(i8*) nounwind

7
test/CodeGen/ARM/thumb1_return_sequence.ll
View File

@ -46,6 +46,7 @@ entry:
store <4 x i32> <i32 42, i32 42, i32 42, i32 42>, <4 x i32>* %b, align 16
store <4 x i32> <i32 0, i32 1, i32 2, i32 3>, <4 x i32>* %a, align 16
%0 = load <4 x i32>* %a, align 16
call void @llvm.va_start(i8* null)
ret <4 x i32> %0
; Epilogue
@ -154,6 +155,7 @@ entry:
%7 = load i32* %d, align 4
%add5 = add nsw i32 %add4, %7
%add6 = add nsw i32 %add5, %i
call void @llvm.va_start(i8* null)
ret i32 %add6
; Epilogue
@ -198,7 +200,8 @@ entry:
; CHECK-V5T: sub sp,
; CHECK-V5T: push {[[SAVED:(r[4567](, )?)+]], lr}
ret i32 %i;
call void @llvm.va_start(i8* null)
ret i32 %i;
; Epilogue
; --------
; CHECK-V4T: pop {[[SAVED]]}
@ -210,3 +213,5 @@ entry:
; CHECK-V5T-NEXT: add sp,
; CHECK-V5T-NEXT: bx r3
}
declare void @llvm.va_start(i8*) nounwind

10
test/CodeGen/ARM/vararg_no_start.ll Normal file
View File

@ -0,0 +1,10 @@
; RUN: llc -mtriple=arm-darwin < %s | FileCheck %s
; RUN: llc -O0 -mtriple=arm-darwin < %s | FileCheck %s
define void @foo(i8*, ...) {
ret void
}
; CHECK-LABEL: {{^_?}}foo:
; CHECK-NOT: str
; CHECK: {{bx lr|mov pc, lr}}
declare void @llvm.va_start(i8*) nounwind

3
test/CodeGen/ARM/vargs_align.ll
View File

@ -10,6 +10,7 @@ entry:
store i32 0, i32* %tmp
%tmp1 = load i32* %tmp ; <i32> [#uses=1]
store i32 %tmp1, i32* %retval
call void @llvm.va_start(i8* null)
br label %return
return: ; preds = %entry
@ -20,3 +21,5 @@ return: ; preds = %entry
; OABI: add sp, sp, #12
; OABI: add sp, sp, #12
}
declare void @llvm.va_start(i8*) nounwind

6
test/CodeGen/Thumb/pop.ll
View File

@ -7,7 +7,9 @@ define void @t(i8* %a, ...) nounwind {
; CHECK-NEXT: add sp, #12
; CHECK-NEXT: bx r3
entry:
%a.addr = alloca i8*
store i8* %a, i8** %a.addr
%a.addr = alloca i8, i32 4
call void @llvm.va_start(i8* %a.addr)
ret void
}
declare void @llvm.va_start(i8*) nounwind

3
test/CodeGen/Thumb2/2009-08-06-SpDecBug.ll
View File

@ -13,6 +13,7 @@ entry:
; CHECK-NOT: mov sp, r7
; CHECK: add sp, #8
call void @__gcov_flush() nounwind
call void @llvm.va_start(i8* null)
br i1 undef, label %bb5, label %bb
bb: ; preds = %bb, %entry
@ -27,3 +28,5 @@ bb5: ; preds = %bb, %entry
declare hidden void @__gcov_flush()
declare i32 @execvp(i8*, i8**) nounwind
declare void @llvm.va_start(i8*) nounwind

9
test/CodeGen/X86/vararg_no_start.ll Normal file
View File

@ -0,0 +1,9 @@
; RUN: llc -mtriple=x86_64-linux < %s | FileCheck %s
; RUN: llc -mtriple=x86_64-windows-msvc < %s | FileCheck %s
define void @foo(i8*, ...) {
ret void
}
; CHECK-LABEL: {{^_?}}foo:
; CHECK-NOT: movq
; CHECK: retq

2
test/CodeGen/X86/vastart-defs-eflags.ll
View File

@ -14,6 +14,7 @@ entry:
br i1 %tobool, label %if.end, label %if.then
if.then: ; preds = %entry
call void @llvm.va_start(i8* null)
br label %if.end
if.end: ; preds = %entry, %if.then
@ -21,3 +22,4 @@ if.end: ; preds = %entry, %if.then
ret i32 %hasflag
}
declare void @llvm.va_start(i8*) nounwind