9e0c06d708
Let Clang emit `dead_on_return` attribute on pointer arguments that are passed indirectly, namely, large aggregates that the ABI mandates be passed by value; thus, the parameter is destroyed within the callee. Writes to such arguments are not observable by the caller after the callee returns. This should desirably enable further MemCpyOpt/DSE optimizations. Previous discussion: https://discourse.llvm.org/t/rfc-add-dead-on-return-attribute/86871.
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 dead_on_return noundef %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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