[PowerPC] Restore stack ptr from frame ptr with setjmp

If a function happens to:

- call setjmp
- do a 16-byte stack allocation
- call a function that sets up a stack frame and longjmp's back

The stack pointer that is restores by setjmp will no longer point to a valid
back chain. According to the ABI, stack accesses in such a function are to be
frame pointer based - so it is an error (quite obviously) to restore the stack
from the back chain.
We already restore the stack from the frame pointer when there are calls to
fast_cc functions. We just need to also do that when there are calls to setjmp.
This patch simply does that.

This was pointed out by the Julia team.

Differential revision: https://reviews.llvm.org/D92906
This commit is contained in:
Nemanja Ivanovic 2020-12-14 11:33:46 -06:00
parent ecab63894b
commit bfdc19e778
2 changed files with 164 additions and 7 deletions

View File

@ -375,9 +375,10 @@ bool PPCFrameLowering::needsFP(const MachineFunction &MF) const {
return false;
return MF.getTarget().Options.DisableFramePointerElim(MF) ||
MFI.hasVarSizedObjects() || MFI.hasStackMap() || MFI.hasPatchPoint() ||
(MF.getTarget().Options.GuaranteedTailCallOpt &&
MF.getInfo<PPCFunctionInfo>()->hasFastCall());
MFI.hasVarSizedObjects() || MFI.hasStackMap() || MFI.hasPatchPoint() ||
MF.exposesReturnsTwice() ||
(MF.getTarget().Options.GuaranteedTailCallOpt &&
MF.getInfo<PPCFunctionInfo>()->hasFastCall());
}
void PPCFrameLowering::replaceFPWithRealFP(MachineFunction &MF) const {
@ -584,8 +585,8 @@ bool PPCFrameLowering::stackUpdateCanBeMoved(MachineFunction &MF) const {
// Frame pointers and base pointers complicate matters so don't do anything
// if we have them. For example having a frame pointer will sometimes require
// a copy of r1 into r31 and that makes keeping track of updates to r1 more
// difficult.
if (hasFP(MF) || RegInfo->hasBasePointer(MF))
// difficult. Similar situation exists with setjmp.
if (hasFP(MF) || RegInfo->hasBasePointer(MF) || MF.exposesReturnsTwice())
return false;
// Calls to fast_cc functions use different rules for passing parameters on
@ -1646,8 +1647,8 @@ void PPCFrameLowering::emitEpilogue(MachineFunction &MF,
// If this function contained a fastcc call and GuaranteedTailCallOpt is
// enabled (=> hasFastCall()==true) the fastcc call might contain a tail
// call which invalidates the stack pointer value in SP(0). So we use the
// value of R31 in this case.
if (FI->hasFastCall()) {
// value of R31 in this case. Similar situation exists with setjmp.
if (FI->hasFastCall() || MF.exposesReturnsTwice()) {
assert(HasFP && "Expecting a valid frame pointer.");
if (!HasRedZone)
RBReg = FPReg;

View File

@ -0,0 +1,156 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc < %s -mtriple=powerpc64le-- -verify-machineinstrs | FileCheck %s
; RUN: llc < %s -mtriple=powerpc64-- -verify-machineinstrs | FileCheck %s \
; RUN: --check-prefix=BE
%struct.__jmp_buf_tag = type { [64 x i64], i32, %struct.__sigset_t, [8 x i8] }
%struct.__sigset_t = type { [16 x i64] }
@.str = private unnamed_addr constant [33 x i8] c"Successfully returned from main\0A\00", align 1
; Function Attrs: nounwind
define dso_local signext i32 @main(i32 signext %argc, i8** nocapture readnone %argv) local_unnamed_addr #0 {
; CHECK-LABEL: main:
; CHECK: # %bb.0: # %entry
; CHECK-NEXT: mfocrf 12, 32
; CHECK-NEXT: mflr 0
; CHECK-NEXT: std 31, -8(1)
; CHECK-NEXT: std 0, 16(1)
; CHECK-NEXT: stw 12, 8(1)
; CHECK-NEXT: stdu 1, -784(1)
; CHECK-NEXT: # kill: def $r3 killed $r3 killed $x3
; CHECK-NEXT: cmpwi 2, 3, 2
; CHECK-NEXT: mr 31, 1
; CHECK-NEXT: li 3, 0
; CHECK-NEXT: blt 2, .LBB0_3
; CHECK-NEXT: # %bb.1: # %if.end
; CHECK-NEXT: addi 3, 31, 112
; CHECK-NEXT: bl _setjmp
; CHECK-NEXT: nop
; CHECK-NEXT: crmove 20, 10
; CHECK-NEXT: # kill: def $r3 killed $r3 killed $x3
; CHECK-NEXT: cmpwi 3, 0
; CHECK-NEXT: crorc 20, 10, 2
; CHECK-NEXT: crmove 21, 2
; CHECK-NEXT: bc 4, 20, .LBB0_4
; CHECK-NEXT: # %bb.2: # %if.end5
; CHECK-NEXT: addis 3, 2, .L.str@toc@ha
; CHECK-NEXT: addi 3, 3, .L.str@toc@l
; CHECK-NEXT: bl printf
; CHECK-NEXT: nop
; CHECK-NEXT: # kill: def $r3 killed $r3 killed $x3
; CHECK-NEXT: .LBB0_3: # %return
; CHECK-NEXT: extsw 3, 3
; CHECK-NEXT: addi 1, 31, 784
; CHECK-NEXT: ld 0, 16(1)
; CHECK-NEXT: lwz 12, 8(1)
; CHECK-NEXT: ld 31, -8(1)
; CHECK-NEXT: mtocrf 32, 12
; CHECK-NEXT: mtlr 0
; CHECK-NEXT: blr
; CHECK-NEXT: .LBB0_4: # %if.then3
; CHECK-NEXT: ld 4, 0(1)
; CHECK-NEXT: stdu 4, -16(1)
; CHECK-NEXT: addi 3, 1, 96
; CHECK-NEXT: li 4, -1
; CHECK-NEXT: stb 4, 0(3)
; CHECK-NEXT: addi 4, 31, 112
; CHECK-NEXT: bl test
; CHECK-NEXT: nop
;
; BE-LABEL: main:
; BE: # %bb.0: # %entry
; BE-NEXT: mflr 0
; BE-NEXT: std 31, -8(1)
; BE-NEXT: std 0, 16(1)
; BE-NEXT: mfcr 12
; BE-NEXT: stw 12, 8(1)
; BE-NEXT: stdu 1, -800(1)
; BE-NEXT: li 4, 0
; BE-NEXT: # kill: def $r3 killed $r3 killed $x3
; BE-NEXT: cmpwi 2, 3, 2
; BE-NEXT: mr 3, 4
; BE-NEXT: mr 31, 1
; BE-NEXT: blt 2, .LBB0_3
; BE-NEXT: # %bb.1: # %if.end
; BE-NEXT: addi 3, 31, 128
; BE-NEXT: bl _setjmp
; BE-NEXT: nop
; BE-NEXT: crmove 20, 10
; BE-NEXT: # kill: def $r3 killed $r3 killed $x3
; BE-NEXT: cmpwi 3, 0
; BE-NEXT: crorc 20, 10, 2
; BE-NEXT: crmove 21, 2
; BE-NEXT: bc 4, 20, .LBB0_4
; BE-NEXT: # %bb.2: # %if.end5
; BE-NEXT: addis 3, 2, .L.str@toc@ha
; BE-NEXT: addi 3, 3, .L.str@toc@l
; BE-NEXT: bl printf
; BE-NEXT: nop
; BE-NEXT: # kill: def $r3 killed $r3 killed $x3
; BE-NEXT: .LBB0_3: # %return
; BE-NEXT: extsw 3, 3
; BE-NEXT: addi 1, 31, 800
; BE-NEXT: ld 0, 16(1)
; BE-NEXT: lwz 12, 8(1)
; BE-NEXT: ld 31, -8(1)
; BE-NEXT: mtlr 0
; BE-NEXT: mtcrf 32, 12 # cr2
; BE-NEXT: blr
; BE-NEXT: .LBB0_4: # %if.then3
; BE-NEXT: ld 4, 0(1)
; BE-NEXT: stdu 4, -16(1)
; BE-NEXT: addi 3, 1, 112
; BE-NEXT: li 4, -1
; BE-NEXT: stb 4, 0(3)
; BE-NEXT: addi 4, 31, 128
; BE-NEXT: bl test
; BE-NEXT: nop
entry:
%env_buffer = alloca [1 x %struct.__jmp_buf_tag], align 16
%cmp = icmp slt i32 %argc, 2
br i1 %cmp, label %return, label %if.end
if.end: ; preds = %entry
%0 = bitcast [1 x %struct.__jmp_buf_tag]* %env_buffer to i8*
call void @llvm.lifetime.start.p0i8(i64 656, i8* nonnull %0) #5
%arraydecay = getelementptr inbounds [1 x %struct.__jmp_buf_tag], [1 x %struct.__jmp_buf_tag]* %env_buffer, i64 0, i64 0
%call = call signext i32 @_setjmp(%struct.__jmp_buf_tag* nonnull %arraydecay) #6
%cmp1 = icmp ne i32 %argc, 2
%cmp2 = icmp eq i32 %call, 0
%or.cond = and i1 %cmp1, %cmp2
br i1 %or.cond, label %if.then3, label %if.end5
if.then3: ; preds = %if.end
%1 = alloca [8 x i8], align 16
%.sub = getelementptr inbounds [8 x i8], [8 x i8]* %1, i64 0, i64 0
store i8 -1, i8* %.sub, align 16
call void @test(i8* nonnull %.sub, %struct.__jmp_buf_tag* nonnull %arraydecay) #7
unreachable
if.end5: ; preds = %if.end
%call6 = call signext i32 (i8*, ...) @printf(i8* nonnull dereferenceable(1) getelementptr inbounds ([33 x i8], [33 x i8]* @.str, i64 0, i64 0))
call void @llvm.lifetime.end.p0i8(i64 656, i8* nonnull %0) #5
br label %return
return: ; preds = %entry, %if.end5
%retval.0 = phi i32 [ %call6, %if.end5 ], [ 0, %entry ]
ret i32 %retval.0
}
; Function Attrs: argmemonly nofree nosync nounwind willreturn
declare void @llvm.lifetime.start.p0i8(i64 immarg, i8* nocapture)
; Function Attrs: nounwind returns_twice
declare signext i32 @_setjmp(%struct.__jmp_buf_tag*) local_unnamed_addr
; Function Attrs: noreturn
declare void @test(i8*, %struct.__jmp_buf_tag*) local_unnamed_addr
; Function Attrs: nofree nounwind
declare noundef signext i32 @printf(i8* nocapture noundef readonly, ...) local_unnamed_addr
; Function Attrs: argmemonly nofree nosync nounwind willreturn
declare void @llvm.lifetime.end.p0i8(i64 immarg, i8* nocapture)
attributes #0 = { nounwind }
attributes #6 = { nounwind returns_twice }