[llvm] r370409 - [X86] Don't emit unreachable stack adjustments
Reid Kleckner via llvm-commits
llvm-commits at lists.llvm.org
Thu Aug 29 14:24:42 PDT 2019
Author: rnk
Date: Thu Aug 29 14:24:41 2019
New Revision: 370409
URL: http://llvm.org/viewvc/llvm-project?rev=370409&view=rev
Log:
[X86] Don't emit unreachable stack adjustments
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
Added:
llvm/trunk/test/CodeGen/X86/noreturn-call-linux.ll
Modified:
llvm/trunk/lib/Target/X86/X86FrameLowering.cpp
llvm/trunk/test/CodeGen/X86/noreturn-call.ll
Modified: llvm/trunk/lib/Target/X86/X86FrameLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86FrameLowering.cpp?rev=370409&r1=370408&r2=370409&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86FrameLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86FrameLowering.cpp Thu Aug 29 14:24:41 2019
@@ -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(MachineFun
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(MachineFun
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.
Added: llvm/trunk/test/CodeGen/X86/noreturn-call-linux.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/noreturn-call-linux.ll?rev=370409&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/X86/noreturn-call-linux.ll (added)
+++ llvm/trunk/test/CodeGen/X86/noreturn-call-linux.ll Thu Aug 29 14:24:41 2019
@@ -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)
+
Modified: llvm/trunk/test/CodeGen/X86/noreturn-call.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/noreturn-call.ll?rev=370409&r1=370408&r2=370409&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/noreturn-call.ll (original)
+++ llvm/trunk/test/CodeGen/X86/noreturn-call.ll Thu Aug 29 14:24:41 2019
@@ -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 at 8
+; CHECK-NOT: sub
+; CHECK-NOT: add
+; CHECK: # %if.then3
+; CHECK: calll _stdcall_abort at 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)
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