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[X86] Enable shrink-wrapping by default, but keep it disabled for stack frames

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without a frame pointer when unwind may happen.
This is a workaround for a bug in the way we emit the CFI directives for
frameless unwind information. See PR25614.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@255175 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Quentin Colombet 2015-12-09 23:08:18 +00:00
parent 28e18e1782
commit d110e2b4a3
5 changed files with 168 additions and 6 deletions
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6
lib/Target/X86/X86FrameLowering.cpp
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@ -2595,6 +2595,12 @@ bool X86FrameLowering::canUseAsEpilogue(const MachineBasicBlock &MBB) const {
return !flagsNeedToBePreservedBeforeTheTerminators(MBB);
}
bool X86FrameLowering::enableShrinkWrapping(const MachineFunction &MF) const {
// If we may need to emit frameless compact unwind information, give
// up as this is currently broken: PR25614.
return MF.getFunction()->hasFnAttribute(Attribute::NoUnwind) || hasFP(MF);
}
MachineBasicBlock::iterator X86FrameLowering::restoreWin32EHStackPointers(
MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI,
DebugLoc DL, bool RestoreSP) const {

3
lib/Target/X86/X86FrameLowering.h
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@ -134,6 +134,9 @@ public:
/// \p MBB will be correctly handled by the target.
bool canUseAsEpilogue(const MachineBasicBlock &MBB) const override;
/// Returns true if the target will correctly handle shrink wrapping.
bool enableShrinkWrapping(const MachineFunction &MF) const override;
/// convertArgMovsToPushes - This method tries to convert a call sequence
/// that uses sub and mov instructions to put the argument onto the stack
/// into a series of pushes.

10
test/CodeGen/X86/avx-splat.ll
View File

@ -57,19 +57,19 @@ entry:
define <8 x float> @funcE() nounwind {
; CHECK-LABEL: funcE:
; CHECK: ## BB#0: ## %for_exit499
; CHECK-NEXT: pushq %rbp
; CHECK-NEXT: movq %rsp, %rbp
; CHECK-NEXT: andq $-32, %rsp
; CHECK-NEXT: subq $1312, %rsp ## imm = 0x520
; CHECK-NEXT: xorl %eax, %eax
; CHECK-NEXT: ## implicit-def: %YMM0
; CHECK-NEXT: testb %al, %al
; CHECK-NEXT: jne LBB4_2
; CHECK-NEXT: ## BB#1: ## %load.i1247
; CHECK-NEXT: pushq %rbp
; CHECK-NEXT: movq %rsp, %rbp
; CHECK-NEXT: andq $-32, %rsp
; CHECK-NEXT: subq $1312, %rsp ## imm = 0x520
; CHECK-NEXT: vbroadcastss {{[0-9]+}}(%rsp), %ymm0
; CHECK-NEXT: LBB4_2: ## %__load_and_broadcast_32.exit1249
; CHECK-NEXT: movq %rbp, %rsp
; CHECK-NEXT: popq %rbp
; CHECK-NEXT: LBB4_2: ## %__load_and_broadcast_32.exit1249
; CHECK-NEXT: retq
allocas:
%udx495 = alloca [18 x [18 x float]], align 32

2
test/CodeGen/X86/tail-opts.ll
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@ -277,8 +277,8 @@ declare fastcc %union.tree_node* @default_conversion(%union.tree_node*) nounwind
; CHECK-LABEL: foo:
; CHECK: callq func
; CHECK-NEXT: .LBB4_2:
; CHECK-NEXT: popq
; CHECK-NEXT: .LBB4_2:
; CHECK-NEXT: ret
define void @foo(i1* %V) nounwind {

153
test/CodeGen/X86/x86-shrink-wrap-unwind.ll Normal file
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@ -0,0 +1,153 @@
; RUN: llc %s -o - | FileCheck %s --check-prefix=CHECK
;
; This test checks that we do not use shrink-wrapping when
; the function does not have any frame pointer and may unwind.
; This is a workaround for a limitation in the emission of
; the CFI directives, that are not correct in such case.
; PR25614
;
; Note: This test cannot be merged with the shrink-wrapping tests
; because the booleans set on the command line take precedence on
; the target logic that disable shrink-wrapping.
target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128"
target triple = "x86_64-apple-macosx"
; No shrink-wrapping should occur here, until the CFI information are fixed.
; CHECK-LABEL: framelessUnwind:
;
; Prologue code.
; (What we push does not matter. It should be some random sratch register.)
; CHECK: pushq
;
; Compare the arguments and jump to exit.
; After the prologue is set.
; CHECK: movl %edi, [[ARG0CPY:%e[a-z]+]]
; CHECK-NEXT: cmpl %esi, [[ARG0CPY]]
; CHECK-NEXT: jge [[EXIT_LABEL:LBB[0-9_]+]]
;
; Store %a in the alloca.
; CHECK: movl [[ARG0CPY]], 4(%rsp)
; Set the alloca address in the second argument.
; CHECK-NEXT: leaq 4(%rsp), %rsi
; Set the first argument to zero.
; CHECK-NEXT: xorl %edi, %edi
; CHECK-NEXT: callq _doSomething
;
; CHECK: [[EXIT_LABEL]]:
;
; Without shrink-wrapping, epilogue is in the exit block.
; Epilogue code. (What we pop does not matter.)
; CHECK-NEXT: popq
;
; CHECK-NEXT: retq
define i32 @framelessUnwind(i32 %a, i32 %b) #0 {
%tmp = alloca i32, align 4
%tmp2 = icmp slt i32 %a, %b
br i1 %tmp2, label %true, label %false
true:
store i32 %a, i32* %tmp, align 4
%tmp4 = call i32 @doSomething(i32 0, i32* %tmp)
br label %false
false:
%tmp.0 = phi i32 [ %tmp4, %true ], [ %a, %0 ]
ret i32 %tmp.0
}
declare i32 @doSomething(i32, i32*)
attributes #0 = { "no-frame-pointer-elim"="false" }
; Shrink-wrapping should occur here. We have a frame pointer.
; CHECK-LABEL: frameUnwind:
;
; Compare the arguments and jump to exit.
; No prologue needed.
;
; Compare the arguments and jump to exit.
; After the prologue is set.
; CHECK: movl %edi, [[ARG0CPY:%e[a-z]+]]
; CHECK-NEXT: cmpl %esi, [[ARG0CPY]]
; CHECK-NEXT: jge [[EXIT_LABEL:LBB[0-9_]+]]
;
; Prologue code.
; CHECK: pushq %rbp
; CHECK: movq %rsp, %rbp
;
; Store %a in the alloca.
; CHECK: movl [[ARG0CPY]], -4(%rbp)
; Set the alloca address in the second argument.
; CHECK-NEXT: leaq -4(%rbp), %rsi
; Set the first argument to zero.
; CHECK-NEXT: xorl %edi, %edi
; CHECK-NEXT: callq _doSomething
;
; Epilogue code. (What we pop does not matter.)
; CHECK: popq %rbp
;
; CHECK: [[EXIT_LABEL]]:
; CHECK-NEXT: retq
define i32 @frameUnwind(i32 %a, i32 %b) #1 {
%tmp = alloca i32, align 4
%tmp2 = icmp slt i32 %a, %b
br i1 %tmp2, label %true, label %false
true:
store i32 %a, i32* %tmp, align 4
%tmp4 = call i32 @doSomething(i32 0, i32* %tmp)
br label %false
false:
%tmp.0 = phi i32 [ %tmp4, %true ], [ %a, %0 ]
ret i32 %tmp.0
}
attributes #1 = { "no-frame-pointer-elim"="true" }
; Shrink-wrapping should occur here. We do not have to unwind.
; CHECK-LABEL: framelessnoUnwind:
;
; Compare the arguments and jump to exit.
; No prologue needed.
;
; Compare the arguments and jump to exit.
; After the prologue is set.
; CHECK: movl %edi, [[ARG0CPY:%e[a-z]+]]
; CHECK-NEXT: cmpl %esi, [[ARG0CPY]]
; CHECK-NEXT: jge [[EXIT_LABEL:LBB[0-9_]+]]
;
; Prologue code.
; (What we push does not matter. It should be some random sratch register.)
; CHECK: pushq
;
; Store %a in the alloca.
; CHECK: movl [[ARG0CPY]], 4(%rsp)
; Set the alloca address in the second argument.
; CHECK-NEXT: leaq 4(%rsp), %rsi
; Set the first argument to zero.
; CHECK-NEXT: xorl %edi, %edi
; CHECK-NEXT: callq _doSomething
;
; Epilogue code.
; CHECK-NEXT: addq
;
; CHECK: [[EXIT_LABEL]]:
; CHECK-NEXT: retq
define i32 @framelessnoUnwind(i32 %a, i32 %b) #2 {
%tmp = alloca i32, align 4
%tmp2 = icmp slt i32 %a, %b
br i1 %tmp2, label %true, label %false
true:
store i32 %a, i32* %tmp, align 4
%tmp4 = call i32 @doSomething(i32 0, i32* %tmp)
br label %false
false:
%tmp.0 = phi i32 [ %tmp4, %true ], [ %a, %0 ]
ret i32 %tmp.0
}
attributes #2 = { "no-frame-pointer-elim"="false" nounwind }