Skip to content

[InstCombine] Special handle va_copy(dst, src) + va_end(src) #140250

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 2 commits into from
May 17, 2025
Merged

[InstCombine] Special handle va_copy(dst, src) + va_end(src) #140250

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
f55daa8
[InstCombine] Add pre-commit tests. NFC.
dtcxzyw May 16, 2025
fd48c14
[InstCombine] Special handle `va_copy(dst, src) + va_end(src)`
dtcxzyw May 16, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
9 changes: 6 additions & 3 deletions llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -816,9 +816,12 @@ removeTriviallyEmptyRange(IntrinsicInst &EndI, InstCombinerImpl &IC,
}

Instruction *InstCombinerImpl::visitVAEndInst(VAEndInst &I) {
removeTriviallyEmptyRange(I, *this, [](const IntrinsicInst &I) {
return I.getIntrinsicID() == Intrinsic::vastart ||
I.getIntrinsicID() == Intrinsic::vacopy;
removeTriviallyEmptyRange(I, *this, [&I](const IntrinsicInst &II) {
// Bail out on the case where the source va_list of a va_copy is destroyed
// immediately by a follow-up va_end.
return II.getIntrinsicID() == Intrinsic::vastart ||
(II.getIntrinsicID() == Intrinsic::vacopy &&
I.getArgOperand(0) != II.getArgOperand(1));
});
return nullptr;
}
Expand Down
52 changes: 41 additions & 11 deletions llvm/test/Transforms/InstCombine/vararg.ll
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,17 +1,14 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
; RUN: opt < %s -passes=instcombine -S | FileCheck %s

%struct.__va_list = type { ptr, ptr, ptr, i32, i32 }

declare void @llvm.lifetime.start.p0(i64, ptr nocapture)
declare void @llvm.lifetime.end.p0(i64, ptr nocapture)
declare void @llvm.va_start(ptr)
declare void @llvm.va_end(ptr)
declare void @llvm.va_copy(ptr, ptr)

define i32 @func(ptr nocapture readnone %fmt, ...) {
; CHECK-LABEL: @func(
; CHECK: entry:
; CHECK-NEXT: ret i32 0
define void @func(ptr nocapture readnone %fmt, ...) {
; CHECK-LABEL: define void @func(
; CHECK-SAME: ptr readnone captures(none) [[FMT:%.*]], ...) {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: ret void
;
entry:
%va0 = alloca %struct.__va_list, align 8
%va1 = alloca %struct.__va_list, align 8
Expand All @@ -23,6 +20,39 @@ entry:
call void @llvm.lifetime.end.p0(i64 32, ptr %va1)
call void @llvm.va_end(ptr %va0)
call void @llvm.lifetime.end.p0(i64 32, ptr %va0)
ret i32 0
ret void
}

declare void @callee(ptr)

define void @func_destroy_copy_src(ptr nocapture readnone %fmt, ...) {
; CHECK-LABEL: define void @func_destroy_copy_src(
; CHECK-SAME: ptr readnone captures(none) [[FMT:%.*]], ...) {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: [[VA0:%.*]] = alloca [[STRUCT___VA_LIST:%.*]], align 8
; CHECK-NEXT: [[VA1:%.*]] = alloca [[STRUCT___VA_LIST]], align 8
; CHECK-NEXT: call void @llvm.lifetime.start.p0(i64 32, ptr nonnull [[VA0]])
; CHECK-NEXT: call void @llvm.lifetime.start.p0(i64 32, ptr nonnull [[VA1]])
; CHECK-NEXT: call void @llvm.va_start.p0(ptr nonnull [[VA0]])
; CHECK-NEXT: call void @llvm.va_copy.p0(ptr nonnull [[VA1]], ptr nonnull [[VA0]])
; CHECK-NEXT: call void @llvm.va_end.p0(ptr [[VA0]])
; CHECK-NEXT: call void @callee(ptr nonnull [[VA1]])
; CHECK-NEXT: call void @llvm.va_end.p0(ptr [[VA1]])
; CHECK-NEXT: call void @llvm.lifetime.end.p0(i64 32, ptr nonnull [[VA1]])
; CHECK-NEXT: call void @llvm.lifetime.end.p0(i64 32, ptr nonnull [[VA0]])
; CHECK-NEXT: ret void
;
entry:
%va0 = alloca %struct.__va_list, align 8
%va1 = alloca %struct.__va_list, align 8
call void @llvm.lifetime.start.p0(i64 32, ptr %va0)
call void @llvm.lifetime.start.p0(i64 32, ptr %va1)
call void @llvm.va_start(ptr %va0)
call void @llvm.va_copy(ptr %va1, ptr %va0)
call void @llvm.va_end(ptr %va0)
call void @callee(ptr %va1)
call void @llvm.va_end(ptr %va1)
call void @llvm.lifetime.end.p0(i64 32, ptr %va1)
call void @llvm.lifetime.end.p0(i64 32, ptr %va0)
ret void
}
Loading