2d00c73003
Fixes the issue reported following the merge of #118026. When a valid `musttail` call is made, the function it is made from must return immediately after the call; if there are any cleanups left in the function, then an error is triggered. This is not necessary for fake uses however - it is perfectly valid to simply emit the fake use "cleanup" code before the tail call, and indeed LLVM will automatically move any fake uses following a tail call to come before the tail call. Therefore, this patch specifically choose to handle fake use cleanups when a musttail call is present by simply emitting them immediately before the call.
28 lines
1.1 KiB
C++
28 lines
1.1 KiB
C++
// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -fextend-variable-liveness -o - %s | FileCheck %s
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/// Tests that when we have fake uses in a function ending in a musttail call,
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/// we emit the fake uses and their corresponding loads immediately prior to the
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/// tail call.
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extern "C" char *bar(int *);
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// CHECK-LABEL: define dso_local ptr @foo(
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// CHECK-SAME: ptr noundef [[E:%.*]])
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// CHECK-NEXT: [[ENTRY:.*:]]
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// CHECK-NEXT: [[E_ADDR:%.*]] = alloca ptr, align 8
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// CHECK-NEXT: store ptr [[E]], ptr [[E_ADDR]], align 8
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// CHECK-NEXT: [[TMP0:%.*]] = load ptr, ptr [[E_ADDR]], align 8
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// CHECK-NEXT: [[FAKE_USE:%.*]] = load ptr, ptr [[E_ADDR]]
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// CHECK-NEXT: notail call void (...) @llvm.fake.use(ptr [[FAKE_USE]])
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// CHECK-NEXT: [[CALL:%.*]] = musttail call ptr @bar(ptr noundef [[TMP0]])
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// CHECK-NEXT: ret ptr [[CALL]]
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// CHECK: [[BB1:.*:]]
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// CHECK-NEXT: [[FAKE_USE1:%.*]] = load ptr, ptr [[E_ADDR]]
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// CHECK-NEXT: notail call void (...) @llvm.fake.use(ptr [[FAKE_USE1]])
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// CHECK-NEXT: ret ptr undef
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//
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extern "C" const char *foo(int *e) {
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[[clang::musttail]] return bar(e);
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}
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