[PATCH] D74713: [ConstantFold] fold most FP ops with undef operand to undef rather than NaN

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added inline comments.


================
Comment at: llvm/test/Transforms/InstSimplify/fp-undef.ll:211-212
 define float @fadd_undef_op0_nnan_constant(float %x) {
 ; CHECK-LABEL: @fadd_undef_op0_nnan_constant(
-; CHECK-NEXT:    ret float 0x7FF8000000000000
+; CHECK-NEXT:    ret float undef
 ;
----------------
This is correct
```
----------------------------------------
define float @fadd_undef_op0_nnan_constant(float %x) {
%0:
  %r = fadd nnan float undef, 1.000000
  ret float %r
}
=>
define float @fadd_undef_op0_nnan_constant(float %x) {
%0:
  %r = fadd nnan float undef, 1.000000
  ret float undef
}
Transformation seems to be correct!

Summary:
  1 correct transformations
  0 incorrect transformations
  0 errors

```


================
Comment at: llvm/test/Transforms/InstSimplify/fp-undef.ll:218-224
 define float @fadd_undef_op1_constant(float %x) {
 ; CHECK-LABEL: @fadd_undef_op1_constant(
-; CHECK-NEXT:    ret float 0x7FF8000000000000
+; CHECK-NEXT:    ret float undef
 ;
   %r = fadd float 2.0, undef
   ret float %r
 }
----------------
This is not correct
```
----------------------------------------
define float @fadd_undef_op1_constant(float %x) {
%0:
  %r = fadd float 2.000000, undef
  ret float %r
}
=>
define float @fadd_undef_op1_constant(float %x) {
%0:
  %r = fadd float 2.000000, undef
  ret float undef
}
Transformation doesn't verify!
ERROR: Value mismatch

Example:
float %x = poison

Source:
float %r = NaN  [based on undef value]

Target:
float %r = NaN  [based on undef value]
Source value: NaN
Target value: #x84000400 (-0.000000000000?)

Summary:
  0 correct transformations
  1 incorrect transformations
  0 errors

```


================
Comment at: llvm/test/Transforms/InstSimplify/fp-undef.ll:234-240
 define float @fsub_undef_op1_constant(float %x) {
 ; CHECK-LABEL: @fsub_undef_op1_constant(
-; CHECK-NEXT:    ret float 0x7FF8000000000000
+; CHECK-NEXT:    ret float undef
 ;
   %r = fsub float 4.0, undef
   ret float %r
 }
----------------
Again, no
```
----------------------------------------
define float @fsub_undef_op1_constant(float %x) {
%0:
  %r = fsub float 4.000000, undef
  ret float %r
}
=>
define float @fsub_undef_op1_constant(float %x) {
%0:
  %r = fsub float 4.000000, undef
  ret float undef
}
Transformation doesn't verify!
ERROR: Value mismatch

Example:
float %x = poison

Source:
float %r = NaN  [based on undef value]

Target:
float %r = NaN  [based on undef value]
Source value: NaN
Target value: #x84000400 (-0.000000000000?)

Summary:
  0 correct transformations
  1 incorrect transformations
  0 errors

```



================
Comment at: llvm/test/Transforms/InstSimplify/fp-undef.ll:242-248
 define float @fmul_undef_op0_nnan_constant(float %x) {
 ; CHECK-LABEL: @fmul_undef_op0_nnan_constant(
-; CHECK-NEXT:    ret float 0x7FF8000000000000
+; CHECK-NEXT:    ret float undef
 ;
   %r = fmul nnan float undef, 5.0
   ret float %r
 }
----------------
This is correct


================
Comment at: llvm/test/Transforms/InstSimplify/fp-undef.ll:250-256
 define float @fmul_undef_op1_constant(float %x) {
 ; CHECK-LABEL: @fmul_undef_op1_constant(
-; CHECK-NEXT:    ret float 0x7FF8000000000000
+; CHECK-NEXT:    ret float undef
 ;
   %r = fmul float 6.0, undef
   ret float %r
 }
----------------
No
```
----------------------------------------
define float @fmul_undef_op1_constant(float %x) {
%0:
  %r = fmul float 6.000000, undef
  ret float %r
}
=>
define float @fmul_undef_op1_constant(float %x) {
%0:
  %r = fmul float 6.000000, undef
  ret float undef
}
Transformation doesn't verify!
ERROR: Value mismatch

Example:
float %x = poison

Source:
float %r = NaN  [based on undef value]

Target:
float %r = NaN  [based on undef value]
Source value: NaN
Target value: #x00001000 (0.000000000000?)

Summary:
  0 correct transformations
  1 incorrect transformations
  0 errors

```


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D74713/new/

https://reviews.llvm.org/D74713