e2d7cd685d
This patch makes the dead_on_return parameter attribute optionally require a number
of bytes to be passed in to specify the number of bytes known to be dead
upon function return/unwind. This is aimed at enabling annotating the
this pointer in C++ destructors with dead_on_return in clang. We need
this to handle cases like the following:
```
struct X {
int n;
~X() {
this[n].n = 0;
}
};
void f() {
X xs[] = {42, -1};
}
```
Where we only certain that sizeof(X) bytes are dead upon return of ~X.
Otherwise DSE would be able to eliminate the store in ~X which would not
be correct.
This patch only does the wiring within IR. Future patches will make
clang emit correct sizing information and update DSE to only delete
stores to objects marked dead_on_return that are provably in bounds of
the number of bytes specified to be dead_on_return.
Reviewers: nikic, alinas, antoniofrighetto
Pull Request: https://github.com/llvm/llvm-project/pull/171712
53 lines
1.4 KiB
C
53 lines
1.4 KiB
C
// RUN: %clang_cc1 -target-feature +altivec -triple powerpc64-unknown-linux-gnu -emit-llvm -o - %s | FileCheck %s
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typedef short v2i16 __attribute__((vector_size (4)));
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typedef short v3i16 __attribute__((vector_size (6)));
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typedef short v4i16 __attribute__((vector_size (8)));
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typedef short v6i16 __attribute__((vector_size (12)));
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typedef short v8i16 __attribute__((vector_size (16)));
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typedef short v16i16 __attribute__((vector_size (32)));
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struct v16i16 { v16i16 x; };
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// CHECK: define{{.*}} i32 @test_v2i16(i32 noundef %x.coerce)
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v2i16 test_v2i16(v2i16 x)
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{
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return x;
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}
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// CHECK: define{{.*}} i64 @test_v3i16(i64 %x.coerce)
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v3i16 test_v3i16(v3i16 x)
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{
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return x;
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}
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// CHECK: define{{.*}} i64 @test_v4i16(i64 noundef %x.coerce)
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v4i16 test_v4i16(v4i16 x)
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{
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return x;
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}
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// CHECK: define{{.*}} <6 x i16> @test_v6i16(<6 x i16> noundef %x)
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v6i16 test_v6i16(v6i16 x)
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{
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return x;
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}
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// CHECK: define{{.*}} <8 x i16> @test_v8i16(<8 x i16> noundef %x)
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v8i16 test_v8i16(v8i16 x)
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{
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return x;
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}
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// CHECK: define{{.*}} void @test_v16i16(ptr dead_on_unwind noalias writable sret(<16 x i16>) align 32 %agg.result, ptr noundef dead_on_return %0)
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v16i16 test_v16i16(v16i16 x)
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{
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return x;
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}
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// CHECK: define{{.*}} void @test_struct_v16i16(ptr dead_on_unwind noalias writable sret(%struct.v16i16) align 32 %agg.result, [2 x i128] %x.coerce)
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struct v16i16 test_struct_v16i16(struct v16i16 x)
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{
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return x;
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}
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