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[framelowering] Improve tracking of first CS pop instruction. 

Summary: This patch makes sure FirstCSPop and MBBI never point to DBG_VALUE instructions, which affected the code generated.

Reviewers: mkuper, aprantl, MatzeB

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D27343

llvm-svn: 288794
This commit is contained in:
Florian Hahn 2016-12-06 10:24:55 +00:00
parent 6aeb249891
commit 7582c669bd
2 changed files with 49 additions and 5 deletions
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13
llvm/lib/Target/X86/X86FrameLowering.cpp
View File

@ -1550,19 +1550,22 @@ void X86FrameLowering::emitEpilogue(MachineFunction &MF,
}
uint64_t SEHStackAllocAmt = NumBytes;
MachineBasicBlock::iterator FirstCSPop = MBBI;
// Skip the callee-saved pop instructions.
while (MBBI != MBB.begin()) {
MachineBasicBlock::iterator PI = std::prev(MBBI);
unsigned Opc = PI->getOpcode();
if ((Opc != X86::POP32r || !PI->getFlag(MachineInstr::FrameDestroy)) &&
(Opc != X86::POP64r || !PI->getFlag(MachineInstr::FrameDestroy)) &&
Opc != X86::DBG_VALUE && !PI->isTerminator())
break;
if (Opc != X86::DBG_VALUE && !PI->isTerminator()) {
if ((Opc != X86::POP32r || !PI->getFlag(MachineInstr::FrameDestroy)) &&
(Opc != X86::POP64r || !PI->getFlag(MachineInstr::FrameDestroy)))
break;
FirstCSPop = PI;
}
--MBBI;
}
MachineBasicBlock::iterator FirstCSPop = MBBI;
MBBI = FirstCSPop;
if (TargetMBB) {
// Fill EAX/RAX with the address of the target block.

41
llvm/test/CodeGen/X86/frame-lowering-debug-intrinsic.ll Normal file
View File

@ -0,0 +1,41 @@
; Test ensuring debug intrinsics do not affect generated function prologue.
;
; RUN: llc -O1 -mtriple=x86_64-unknown-unknown -o - %s | FileCheck %s
define i64 @noDebug(i64 %a) {
%call = call i64 @fn(i64 %a, i64 0)
ret i64 %call
}
; CHECK-LABEL: noDebug
; CHECK: popq %rcx
; CHECK: ret
define i64 @withDebug(i64 %a) !dbg !4 {
%call = call i64 @fn(i64 %a, i64 0)
tail call void @llvm.dbg.value(metadata i64 %call, i64 0, metadata !5, metadata !6), !dbg !7
ret i64 %call
}
; CHECK-LABEL: withDebug
; CHECK: popq %rcx
; CHECK: ret
declare i64 @fn(i64, i64)
declare void @llvm.dbg.value(metadata, i64, metadata, metadata)
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!2,!3}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 4.0.0")
!1 = !DIFile(filename: "test.c", directory: "/")
!2 = !{i32 2, !"Dwarf Version", i32 4}
!3 = !{i32 2, !"Debug Info Version", i32 3}
!4 = distinct !DISubprogram(name: "withDebug", unit: !0)
!5 = !DILocalVariable(name: "w", scope: !4)
!6 = !DIExpression()
!7 = !DILocation(line: 210, column: 12, scope: !4)