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[SjLjEHPrepare] Configure call sites correctly #117656

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Nov 27, 2024
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[SjLjEHPrepare] Configure call sites correctly #117656

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a89eed9
[SjLjEHPrepare] Configure call sites correctly
s-barannikov Nov 26, 2024
3c823a2
Update VE tests
s-barannikov Nov 26, 2024
e27b7fd
Make the test representative
s-barannikov Nov 26, 2024
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11 changes: 5 additions & 6 deletions llvm/lib/CodeGen/SjLjEHPrepare.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -435,6 +435,10 @@ bool SjLjEHPrepareImpl::setupEntryBlockAndCallSites(Function &F) {
// where to look for it.
Builder.CreateCall(FuncCtxFn, FuncCtx);

// Register the function context and make sure it's known to not throw.
CallInst *Register = Builder.CreateCall(RegisterFn, FuncCtx, "");
Register->setDoesNotThrow();

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@s-barannikov s-barannikov Nov 26, 2024

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This NFC change wasn't strictly necessary, but with it the generated code becomes more logical/structured (setting up call sites right before associated calls).

// At this point, we are all set up, update the invoke instructions to mark
// their call_site values.
for (unsigned I = 0, E = Invokes.size(); I != E; ++I) {
Expand All @@ -457,15 +461,10 @@ bool SjLjEHPrepareImpl::setupEntryBlockAndCallSites(Function &F) {
if (&BB == &F.front())
continue;
for (Instruction &I : BB)
if (I.mayThrow())
if (!isa<InvokeInst>(I) && I.mayThrow())
insertCallSiteStore(&I, -1);
}

// Register the function context and make sure it's known to not throw
CallInst *Register = CallInst::Create(
RegisterFn, FuncCtx, "", EntryBB->getTerminator()->getIterator());
Register->setDoesNotThrow();

// Following any allocas not in the entry block, update the saved SP in the
// jmpbuf to the new value.
for (BasicBlock &BB : F) {
Expand Down
4 changes: 4 additions & 0 deletions llvm/test/CodeGen/ARM/sjljehprepare-lower-empty-struct.ll
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Expand Up @@ -16,11 +16,15 @@
define ptr @foo(i8 %a, {} %c) personality ptr @baz {
entry:
; CHECK: bl __Unwind_SjLj_Register
; CHECK-NEXT: mov r0, #1
; CHECK-NEXT: str r0, [sp, #{{[0-9]+}}]
; CHECK-NEXT: {{[A-Z][a-zA-Z0-9]*}}:
; CHECK-NEXT: bl _bar
; CHECK: bl __Unwind_SjLj_Resume

; CHECK-LINUX: bl _Unwind_SjLj_Register
; CHECK-LINUX-NEXT: mov r0, #1
; CHECK-LINUX-NEXT: str r0, [sp, #{{[0-9]+}}]
; CHECK-LINUX-NEXT: .{{[A-Z][a-zA-Z0-9]*}}:
; CHECK-LINUX-NEXT: bl bar
; CHECK-LINUX: bl _Unwind_SjLj_Resume
Expand Down
40 changes: 40 additions & 0 deletions llvm/test/CodeGen/Generic/sjlj-eh-prepare.ll
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@@ -0,0 +1,40 @@
; RUN: opt -p sjlj-eh-prepare %s -S -o - | FileCheck %s

; Check that callsites are set up correctly:
; 1. Throwing call in the entry block does not set call_site
; (function context hasn't been configured yet).
; 2. Throwing call not in the entry block sets call_site to -1
; (reset to the initial state).
; 3. Invoke instructions set call_site to the correct call site number.
; 4. Resume instruction sets call_site to -1 (reset to the initial state).

define void @test_call_sites() personality ptr @__gxx_personality_sj0 {
entry:
; CHECK-NOT: store volatile
; CHECK: call void @may_throw()
call void @may_throw()

; CHECK: store volatile i32 1
; CHECK-NEXT: call void @llvm.eh.sjlj.callsite(i32 1)
; CHECK-NEXT: invoke void @may_throw()
invoke void @may_throw() to label %invoke.cont unwind label %lpad

invoke.cont:
; CHECK: store volatile i32 2
; CHECK-NEXT: call void @llvm.eh.sjlj.callsite(i32 2)
; CHECK-NEXT: invoke void @may_throw()
invoke void @may_throw() to label %try.cont unwind label %lpad
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@s-barannikov s-barannikov Nov 26, 2024

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IR before this change:

invoke.cont:                                      ; preds = %entry
  %call_site2 = getelementptr { ptr, i32, [4 x i32], ptr, ptr, [5 x ptr] }, ptr %fn_context, i32 0, i32 1
  store volatile i32 2, ptr %call_site2, align 4
  call void @llvm.eh.sjlj.callsite(i32 2)
  %call_site3 = getelementptr { ptr, i32, [4 x i32], ptr, ptr, [5 x ptr] }, ptr %fn_context, i32 0, i32 1
  store volatile i32 -1, ptr %call_site3, align 4
  invoke void @may_throw()
          to label %try.cont unwind label %lpad


lpad:
; CHECK: store volatile i32 -1
; CHECK-NEXT: resume
%lp = landingpad { ptr, i32 } cleanup
resume { ptr, i32 } %lp

try.cont:
call void @may_throw()
ret void
}

declare void @may_throw()
declare i32 @__gxx_personality_sj0(...)
4 changes: 2 additions & 2 deletions llvm/test/CodeGen/X86/indirect-branch-tracking-eh2.ll
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Expand Up @@ -24,9 +24,9 @@ define dso_local i32 @main() #0 personality ptr @__gxx_personality_sj0 {
; NUM-NEXT: movq %rbp, -104(%rbp)
; NUM-NEXT: movq %rsp, -88(%rbp)
; NUM-NEXT: movq $.LBB0_9, -96(%rbp)
; NUM-NEXT: movl $1, -144(%rbp)
; NUM-NEXT: leaq -152(%rbp), %rdi
; NUM-NEXT: callq _Unwind_SjLj_Register@PLT
; NUM-NEXT: movl $1, -144(%rbp)
; NUM-NEXT: .Ltmp0:
; NUM-NEXT: callq _Z3foov
; NUM-NEXT: .Ltmp1:
Expand Down Expand Up @@ -110,9 +110,9 @@ define dso_local i32 @main() #0 personality ptr @__gxx_personality_sj0 {
; SJLJ-NEXT: movq %rbp, -104(%rbp)
; SJLJ-NEXT: movq %rsp, -88(%rbp)
; SJLJ-NEXT: movq $.LBB0_9, -96(%rbp)
; SJLJ-NEXT: movl $1, -144(%rbp)
; SJLJ-NEXT: leaq -152(%rbp), %rdi
; SJLJ-NEXT: callq _Unwind_SjLj_Register@PLT
; SJLJ-NEXT: movl $1, -144(%rbp)
; SJLJ-NEXT: .Ltmp0:
; SJLJ-NEXT: callq _Z3foov
; SJLJ-NEXT: .Ltmp1:
Expand Down
6 changes: 2 additions & 4 deletions llvm/test/CodeGen/X86/sjlj-eh.ll
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Expand Up @@ -48,14 +48,13 @@ try.cont:
; CHECK: movl %esp, -24(%ebp)
; UFC.__jbuf[1] = $EIP
; CHECK: movl $[[RESUME:LBB[0-9]+_[0-9]+]], -28(%ebp)
; UFC.__callsite = 1
; CHECK: movl $1, -60(%ebp)
; _Unwind_SjLj_Register(&UFC);
; CHECK: leal -64(%ebp), %eax
; CHECK: pushl %eax
; CHECK: calll __Unwind_SjLj_Register
; CHECK: addl $4, %esp
; function_that_throws();
; CHECK: movl $1, -60(%ebp)
; CHECK: calll __Z20function_that_throwsv
; _Unwind_SjLj_Unregister(&UFC);
; CHECK: leal -64(%ebp), %eax
Expand Down Expand Up @@ -99,12 +98,11 @@ try.cont:
; UFC.__jbuf[1] = $RIP
; CHECK-X64: leaq .[[RESUME:LBB[0-9]+_[0-9]+]](%rip), %rax
; CHECK-X64: movq %rax, -256(%rbp)
; UFC.__callsite = 1
; CHECK-X64: movl $1, -304(%rbp)
; _Unwind_SjLj_Register(&UFC);
; CHECK-X64: leaq -312(%rbp), %rcx
; CHECK-X64: callq _Unwind_SjLj_Register
; function_that_throws();
; CHECK-X64: movl $1, -304(%rbp)
; CHECK-X64: callq _Z20function_that_throwsv
; _Unwind_SjLj_Unregister(&UFC);
; CHECK-X64: leaq -312(%rbp), %rcx
Expand Down
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