10264a1b21
This change adds a new IR noundef attribute, which denotes when a function call argument or return val may never contain uninitialized bits. In MemorySanitizer, this attribute enables optimizations which decrease instrumented code size by up to 17% (measured with an instrumented build of clang) . I'll introduce the change allowing msan to take advantage of this information in a separate patch. Differential Revision: https://reviews.llvm.org/D81678
35 lines
1.1 KiB
C++
35 lines
1.1 KiB
C++
// RUN: %clang -cc1 -x c++ -triple x86_64-unknown-unknown -O0 -emit-llvm -enable-noundef-analysis -o - %s | FileCheck %s
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union u1 {
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int val;
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};
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// CHECK: @indirect_callee_int_ptr = [[GLOBAL:(dso_local )?global]] i32 (i32)*
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int (*indirect_callee_int_ptr)(int);
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// CHECK: @indirect_callee_union_ptr = [[GLOBAL]] i32 (i32)*
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union u1 (*indirect_callee_union_ptr)(union u1);
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// CHECK: [[DEFINE:define( dso_local)?]] noundef i32 @{{.*}}indirect_callee_int{{.*}}(i32 noundef %
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int indirect_callee_int(int a) { return a; }
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// CHECK: [[DEFINE]] i32 @{{.*}}indirect_callee_union{{.*}}(i32 %
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union u1 indirect_callee_union(union u1 a) {
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return a;
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}
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int main() {
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// CHECK: call noundef i32 @{{.*}}indirect_callee_int{{.*}}(i32 noundef 0)
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indirect_callee_int(0);
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// CHECK: call i32 @{{.*}}indirect_callee_union{{.*}}(i32 %
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indirect_callee_union((union u1){0});
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indirect_callee_int_ptr = indirect_callee_int;
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indirect_callee_union_ptr = indirect_callee_union;
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// CHECK: call noundef i32 %{{.*}}(i32 noundef 0)
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indirect_callee_int_ptr(0);
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// CHECK: call i32 %{{.*}}(i32 %
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indirect_callee_union_ptr((union u1){});
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return 0;
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}
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