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[X86] Don't emit unreachable stack adjustments

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Summary:
This is a minor improvement on our past attempts to do this. Fixes
PR43155.

Reviewers: hans

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D66905

llvm-svn: 370409
This commit is contained in:
Reid Kleckner 2019-08-29 21:24:41 +00:00
parent a3a536f2f0
commit 3d21854d5e
3 changed files with 129 additions and 2 deletions
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16
lib/Target/X86/X86FrameLowering.cpp
View File

@ -2550,6 +2550,18 @@ static unsigned getHiPELiteral(
+ " required but not provided");
}
// Return true if there are no non-ehpad successors to MBB and there are no
// non-meta instructions between MBBI and MBB.end().
bool blockEndIsUnreachable(const MachineBasicBlock &MBB,
MachineBasicBlock::const_iterator MBBI) {
return std::all_of(
MBB.succ_begin(), MBB.succ_end(),
[](const MachineBasicBlock *Succ) { return Succ->isEHPad(); }) &&
std::all_of(MBBI, MBB.end(), [](const MachineInstr &MI) {
return MI.isMetaInstruction();
});
}
/// Erlang programs may need a special prologue to handle the stack size they
/// might need at runtime. That is because Erlang/OTP does not implement a C
/// stack but uses a custom implementation of hybrid stack/heap architecture.
@ -2783,7 +2795,7 @@ eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
unsigned Opcode = I->getOpcode();
bool isDestroy = Opcode == TII.getCallFrameDestroyOpcode();
DebugLoc DL = I->getDebugLoc();
uint64_t Amount = !reserveCallFrame ? TII.getFrameSize(*I) : 0;
uint64_t Amount = TII.getFrameSize(*I);
uint64_t InternalAmt = (isDestroy || Amount) ? TII.getFrameAdjustment(*I) : 0;
I = MBB.erase(I);
auto InsertPos = skipDebugInstructionsForward(I, MBB.end());
@ -2872,7 +2884,7 @@ eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
return I;
}
if (isDestroy && InternalAmt) {
if (isDestroy && InternalAmt && !blockEndIsUnreachable(MBB, I)) {
// If we are performing frame pointer elimination and if the callee pops
// something off the stack pointer, add it back. We do this until we have
// more advanced stack pointer tracking ability.

59
test/CodeGen/X86/noreturn-call-linux.ll Normal file
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@ -0,0 +1,59 @@
; RUN: llc < %s -mtriple=x86_64-linux-gnu | FileCheck %s
; PR43155, we used to emit dead stack adjustments for noreturn calls with stack
; arguments.
; Original source code:
; __attribute__((noreturn)) void exit_manyarg(int, int, int, int, int, int, int, int, int, int);
; struct ByVal {
; int vals[10];
; };
; struct ByVal getbyval();
; void make_push_unprofitable(struct ByVal);
; int foo(int c) {
; if (c)
; exit_manyarg(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
; make_push_unprofitable(getbyval());
; make_push_unprofitable(getbyval());
; make_push_unprofitable(getbyval());
; return 0;
; }
%struct.ByVal = type { [10 x i32] }
define dso_local i32 @foo(i32 %c) {
entry:
%agg.tmp = alloca %struct.ByVal, align 8
%agg.tmp1 = alloca %struct.ByVal, align 8
%agg.tmp2 = alloca %struct.ByVal, align 8
%tobool = icmp eq i32 %c, 0
br i1 %tobool, label %if.end, label %if.then
if.then: ; preds = %entry
tail call void @exit_manyarg(i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 9, i32 10) #3
unreachable
if.end: ; preds = %entry
call void @getbyval(%struct.ByVal* nonnull sret %agg.tmp) #4
call void @make_push_unprofitable(%struct.ByVal* nonnull byval(%struct.ByVal) align 8 %agg.tmp) #4
call void @getbyval(%struct.ByVal* nonnull sret %agg.tmp1) #4
call void @make_push_unprofitable(%struct.ByVal* nonnull byval(%struct.ByVal) align 8 %agg.tmp1) #4
call void @getbyval(%struct.ByVal* nonnull sret %agg.tmp2) #4
call void @make_push_unprofitable(%struct.ByVal* nonnull byval(%struct.ByVal) align 8 %agg.tmp2) #4
ret i32 0
}
; CHECK-LABEL: foo:
; The main body is not important.
; CHECK: callq exit_manyarg
; CHECK-NOT: sub
; CHECK-NOT: add
; CHECK: # -- End function
; Function Attrs: noreturn
declare dso_local void @exit_manyarg(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) noreturn
declare dso_local void @make_push_unprofitable(%struct.ByVal* byval(%struct.ByVal) align 8)
declare dso_local void @getbyval(%struct.ByVal* sret)

56
test/CodeGen/X86/noreturn-call.ll
View File

@ -46,3 +46,59 @@ if.then:
declare void @crash(i8*) noreturn
declare void @crash2(i8*)
declare void @g(i8*)
%struct.ByVal = type { [10 x i32] }
define dso_local i32 @pr43155() {
entry:
%agg.tmp = alloca %struct.ByVal, align 4
%agg.tmp5 = alloca %struct.ByVal, align 4
%agg.tmp6 = alloca %struct.ByVal, align 4
%call = tail call i32 @cond()
%tobool = icmp eq i32 %call, 0
br i1 %tobool, label %if.end, label %if.then
if.then: ; preds = %entry
tail call x86_stdcallcc void @stdcall_abort(i32 12, i32 2)
unreachable
if.end: ; preds = %entry
%call1 = tail call i32 @cond()
%tobool2 = icmp eq i32 %call1, 0
br i1 %tobool2, label %if.end4, label %if.then3
if.then3: ; preds = %if.end
tail call x86_stdcallcc void @stdcall_abort(i32 15, i32 2)
unreachable
if.end4: ; preds = %if.end
call void @getbyval(%struct.ByVal* nonnull sret %agg.tmp)
call void @make_push_unprofitable(%struct.ByVal* nonnull byval(%struct.ByVal) align 4 %agg.tmp)
call void @getbyval(%struct.ByVal* nonnull sret %agg.tmp5)
call void @make_push_unprofitable(%struct.ByVal* nonnull byval(%struct.ByVal) align 4 %agg.tmp5)
call void @getbyval(%struct.ByVal* nonnull sret %agg.tmp6)
call void @make_push_unprofitable(%struct.ByVal* nonnull byval(%struct.ByVal) align 4 %agg.tmp6)
ret i32 0
}
; Check that there are no stack adjustments after stdcall_abort.
; CHECK-LABEL: pr43155:
; The main function body contents are not important.
; CHECK: retl
; CHECK: # %if.then
; CHECK: calll _stdcall_abort@8
; CHECK-NOT: sub
; CHECK-NOT: add
; CHECK: # %if.then3
; CHECK: calll _stdcall_abort@8
; CHECK-NOT: sub
; CHECK-NOT: add
; CHECK: # -- End function
declare dso_local i32 @cond()
declare dso_local x86_stdcallcc void @stdcall_abort(i32, i32) noreturn
declare dso_local void @make_push_unprofitable(%struct.ByVal* byval(%struct.ByVal) align 4)
declare dso_local void @getbyval(%struct.ByVal* sret)