| Issue |
138819
|
| Summary |
InstSimplify: incorrect frexp(frexp(x)) -> frexp(x) fold
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
nunoplopes
|
It's not ok to fold `frexp(frexp(x))` to `frexp(x)`:
```llvm
; Transforms/InstSimplify/frexp.ll
define {float, i32} @frexp_frexp(float %x) {
%frexp0 = frexp float %x
%frexp0.0 = extractvalue {float, i32} %frexp0, 0
%frexp1 = frexp float %frexp0.0
ret {float, i32} %frexp1
}
=>
define {float, i32} @frexp_frexp(float %x) {
%frexp0 = frexp float %x
ret {float, i32} %frexp0
}
Transformation doesn't verify!
ERROR: Value mismatch
Example:
float %x = #x0000000a (0.000000000000?)
Source:
{float, i32} %frexp0 = { #x3f200000 (0.625), #xffffff6f (4294967151, -145) }
float %frexp0.0 = #x3f200000 (0.625)
{float, i32} %frexp1 = { #x3f200000 (0.625), #x00000000 (0) }
Target:
{float, i32} %frexp0 = { #x3f200000 (0.625), #xffffff6f (4294967151, -145) }
Source value: { #x3f200000 (0.625), #x00000000 (0) }
Target value: { #x3f200000 (0.625), #xffffff6f (4294967151, -145) }
```
cc @arsenm
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