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https://github.com/capstone-engine/llvm-capstone.git
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158d72d728
Set the writable and dead_on_unwind attributes for sret arguments. These indicate that the argument points to writable memory (and it's legal to introduce spurious writes to it on entry to the function) and that the argument memory will not be used if the call unwinds. This enables additional MemCpyOpt/DSE/LICM optimizations.
84 lines
2.6 KiB
C
84 lines
2.6 KiB
C
// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -O1 -S -emit-llvm -o - %s | FileCheck %s --check-prefixes=O1
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// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -O0 -S -emit-llvm -o - %s | FileCheck %s --check-prefix=O0
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//
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// Ensure that we place appropriate lifetime markers around indirectly returned
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// temporaries, and that the lifetime.ends appear in a timely manner.
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//
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// -O1 is used so lifetime markers actually get emitted and optnone is added
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// to avoid elimination of lifetime markers by optimizations.
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struct S {
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int ns[40];
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};
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struct S foo(void);
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// CHECK-LABEL: define dso_local void @bar
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__attribute__((optnone))
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struct S bar(void) {
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// O0-NOT: @llvm.lifetime.start
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// O0-NOT: @llvm.lifetime.end
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struct S r;
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// O1: %[[TMP1_ALLOCA:[^ ]+]] = alloca %struct.S
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// O1: %[[TMP2_ALLOCA:[^ ]+]] = alloca %struct.S
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// O1: %[[TMP3_ALLOCA:[^ ]+]] = alloca %struct.S
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// O1: call void @llvm.lifetime.start.p0({{[^,]*}}, ptr %[[TMP1_ALLOCA]])
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// O1: call void @foo
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r = foo();
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// O1: memcpy
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// O1: call void @llvm.lifetime.end.p0({{[^,]*}}, ptr %[[TMP1_ALLOCA]])
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// O1: call void @llvm.lifetime.start.p0({{[^,]*}}, ptr %[[TMP2_ALLOCA]])
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// O1: call void @foo
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r = foo();
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// O1: memcpy
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// O1: call void @llvm.lifetime.end.p0({{[^,]*}}, ptr %[[TMP2_ALLOCA]])
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// O1: call void @llvm.lifetime.start.p0({{[^,]*}}, ptr %[[TMP3_ALLOCA]])
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// O1: call void @foo
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r = foo();
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// O1: memcpy
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// O1: call void @llvm.lifetime.end.p0({{[^,]*}}, ptr %[[TMP3_ALLOCA]])
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return r;
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}
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struct S foo_int(int);
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// Be sure that we're placing the lifetime.end so that all paths go through it.
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// CHECK-LABEL: define dso_local void @baz
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__attribute__((optnone))
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struct S baz(int i, volatile int *j) {
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// O0-NOT: @llvm.lifetime.start
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// O0-NOT: @llvm.lifetime.end
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struct S r;
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// O1: %[[TMP1_ALLOCA:[^ ]+]] = alloca %struct.S
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// O1: %[[TMP2_ALLOCA:[^ ]+]] = alloca %struct.S
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do {
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// O1: call void @llvm.lifetime.start.p0({{[^,]*}}, ptr %[[TMP1_ALLOCA]])
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//
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// O1: call void @llvm.lifetime.end.p0({{[^,]*}}, ptr %[[TMP1_ALLOCA]])
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//
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// O1: call void @foo_int(ptr dead_on_unwind writable sret(%struct.S) align 4 %[[TMP1_ALLOCA]],
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// O1: call void @llvm.memcpy
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// O1: call void @llvm.lifetime.end.p0({{[^,]*}}, ptr %[[TMP1_ALLOCA]])
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// O1: call void @llvm.lifetime.start.p0({{[^,]*}}, ptr %[[TMP2_ALLOCA]])
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// O1: call void @foo_int(ptr dead_on_unwind writable sret(%struct.S) align 4 %[[TMP2_ALLOCA]],
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// O1: call void @llvm.memcpy
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// O1: call void @llvm.lifetime.end.p0({{[^,]*}}, ptr %[[TMP2_ALLOCA]])
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r = foo_int(({
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if (*j)
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break;
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i++;
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}));
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r = foo_int(i++);
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} while (1);
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return r;
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}
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