| Issue |
159905
|
| Summary |
[X86][MMX] ConstExpr function fails to identify sub _expression_ as constant _expression_
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
mahesh-attarde
|
I have test case that seems to regressed for latest constexpr changes.
```
#include<immintrin.h>
constexpr
__m64 foo(__m64 a, int b){
return (__m64)(long long)a << b;
}
int main(){
foo((__m64){5},1);
return 0;
}
```
gcc-trunk works fine. clang-trunk errors out.
```
<source>:3:7: error: constexpr function never produces a constant _expression_ [-Winvalid-constexpr]
3 | __m64 foo(__m64 a, int b){
| ^~~
<source>:4:19: note: subexpression not valid in a constant _expression_
4 | return (__m64)(long long)a << b;
```
Following change passed
```
#include<immintrin.h>
constexpr
__m64 foo(__m64 a, int b){
if(b > 63)
return (__m64){0};
return (__m64)(long long)a << b;
}
int main(){
foo((__m64){5},1);
return 0;
}
```
here is repro https://godbolt.org/z/d7obEcb57
Does anyone know what may be trouble here?
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