[llvm] [AMDGPU] Avoid fract fold when result is observable at +/-inf (PR #219515)

[Matt Arsenault via llvm-commits]

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@@ -523,24 +523,16 @@ entry:
 }
 
 define float @safe_math_fract_f32_noinf_check(float %x, ptr addrspace(1) writeonly captures(none) %ip) {
-; GFX6-IR-LABEL: define float @safe_math_fract_f32_noinf_check(
-; GFX6-IR-SAME: float [[X:%.*]], ptr addrspace(1) writeonly captures(none) [[IP:%.*]]) {
-; GFX6-IR-NEXT:  [[ENTRY:.*:]]
-; GFX6-IR-NEXT:    [[FLOOR:%.*]] = tail call float @llvm.floor.f32(float [[X]])
-; GFX6-IR-NEXT:    [[SUB:%.*]] = fsub float [[X]], [[FLOOR]]
-; GFX6-IR-NEXT:    [[MIN:%.*]] = tail call float @llvm.minnum.f32(float [[SUB]], float f0x3F7FFFFF)
-; GFX6-IR-NEXT:    [[UNO:%.*]] = fcmp uno float [[X]], 0.000000e+00
-; GFX6-IR-NEXT:    [[COND:%.*]] = select i1 [[UNO]], float [[X]], float [[MIN]]
-; GFX6-IR-NEXT:    store float [[FLOOR]], ptr addrspace(1) [[IP]], align 4
-; GFX6-IR-NEXT:    ret float [[COND]]
-;
-; IR-FRACT-LABEL: define float @safe_math_fract_f32_noinf_check(
-; IR-FRACT-SAME: float [[X:%.*]], ptr addrspace(1) writeonly captures(none) [[IP:%.*]]) {
-; IR-FRACT-NEXT:  [[ENTRY:.*:]]
-; IR-FRACT-NEXT:    [[FLOOR:%.*]] = tail call float @llvm.floor.f32(float [[X]])
-; IR-FRACT-NEXT:    [[COND:%.*]] = call float @llvm.amdgcn.fract.f32(float [[X]])
-; IR-FRACT-NEXT:    store float [[FLOOR]], ptr addrspace(1) [[IP]], align 4
-; IR-FRACT-NEXT:    ret float [[COND]]
+; IR-LABEL: define float @safe_math_fract_f32_noinf_check(
+; IR-SAME: float [[X:%.*]], ptr addrspace(1) writeonly captures(none) [[IP:%.*]]) {
+; IR-NEXT:  [[ENTRY:.*:]]
+; IR-NEXT:    [[FLOOR:%.*]] = tail call float @llvm.floor.f32(float [[X]])
+; IR-NEXT:    [[SUB:%.*]] = fsub float [[X]], [[FLOOR]]
+; IR-NEXT:    [[MIN:%.*]] = tail call float @llvm.minnum.f32(float [[SUB]], float f0x3F7FFFFF)
+; IR-NEXT:    [[UNO:%.*]] = fcmp uno float [[X]], 0.000000e+00
+; IR-NEXT:    [[COND:%.*]] = select i1 [[UNO]], float [[X]], float [[MIN]]
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arsenm wrote:

I thought this case was supposed to rewrite to fract + an  inf guard 

https://github.com/llvm/llvm-project/pull/219515