[GlobalIsel] Remove NoNaNsFPMath uses (llvm#163484)

Users should use `nnan` instead.
This is the GlobalIsel part.

Author: paperchalice

llvm/lib/CodeGen/GlobalISel/Utils.cpp

@@ -818,8 +818,7 @@ bool llvm::isKnownNeverNaN(Register Val, const MachineRegisterInfo &MRI,
   if (!DefMI)
     return false;
 
-  const TargetMachine& TM = DefMI->getMF()->getTarget();
-  if (DefMI->getFlag(MachineInstr::FmNoNans) || TM.Options.NoNaNsFPMath)
+  if (DefMI->getFlag(MachineInstr::FmNoNans))
     return true;
 
   // If the value is a constant, we can obviously see if it is a NaN or not.

llvm/test/CodeGen/AMDGPU/GlobalISel/clamp-minmax-const-combine.ll

@@ -206,7 +206,7 @@ define <2 x half> @test_max_K0min_K1Val_v2f16(<2 x half> %a) #1 {
 
 ; global nnan function attribute always forces clamp combine
 
-define float @test_min_max_global_nnan(float %a) #3 {
+define float @test_min_max_global_nnan(float %a) {
 ; GFX10-LABEL: test_min_max_global_nnan:
 ; GFX10:       ; %bb.0:
 ; GFX10-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
@@ -223,11 +223,11 @@ define float @test_min_max_global_nnan(float %a) #3 {
 ; GFX12-NEXT:    v_max_num_f32_e64 v0, v0, v0 clamp
 ; GFX12-NEXT:    s_setpc_b64 s[30:31]
   %maxnum = call float @llvm.maxnum.f32(float %a, float 0.0)
-  %fmed = call float @llvm.minnum.f32(float %maxnum, float 1.0)
+  %fmed = call nnan float @llvm.minnum.f32(float %maxnum, float 1.0)
   ret float %fmed
 }
 
-define float @test_max_min_global_nnan(float %a) #3 {
+define float @test_max_min_global_nnan(float %a) {
 ; GFX10-LABEL: test_max_min_global_nnan:
 ; GFX10:       ; %bb.0:
 ; GFX10-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
@@ -244,7 +244,7 @@ define float @test_max_min_global_nnan(float %a) #3 {
 ; GFX12-NEXT:    v_max_num_f32_e64 v0, v0, v0 clamp
 ; GFX12-NEXT:    s_setpc_b64 s[30:31]
   %minnum = call float @llvm.minnum.f32(float %a, float 1.0)
-  %fmed = call float @llvm.maxnum.f32(float %minnum, float 0.0)
+  %fmed = call nnan float @llvm.maxnum.f32(float %minnum, float 0.0)
   ret float %fmed
 }
 
@@ -414,5 +414,4 @@ declare <2 x half> @llvm.maxnum.v2f16(<2 x half>, <2 x half>)
 attributes #0 = {"amdgpu-ieee"="true"}
 attributes #1 = {"amdgpu-ieee"="false"}
 attributes #2 = {"amdgpu-ieee"="true" "amdgpu-dx10-clamp"="true"}
-attributes #3 = {"no-nans-fp-math"="true"}
 attributes #4 = {"amdgpu-ieee"="true" "amdgpu-dx10-clamp"="false"}

llvm/test/CodeGen/AMDGPU/GlobalISel/fmed3-min-max-const-combine.ll

@@ -232,7 +232,7 @@ define half @test_max_K0min_K1Val_f16(half %a) #1 {
 
 ; global nnan function attribute always forces fmed3 combine
 
-define float @test_min_max_global_nnan(float %a) #2 {
+define float @test_min_max_global_nnan(float %a) {
 ; GFX10-LABEL: test_min_max_global_nnan:
 ; GFX10:       ; %bb.0:
 ; GFX10-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
@@ -254,12 +254,12 @@ define float @test_min_max_global_nnan(float %a) #2 {
 ; GFX12-NEXT:    s_wait_kmcnt 0x0
 ; GFX12-NEXT:    v_med3_num_f32 v0, v0, 2.0, 4.0
 ; GFX12-NEXT:    s_setpc_b64 s[30:31]
-  %maxnum = call float @llvm.maxnum.f32(float %a, float 2.0)
+  %maxnum = call nnan float @llvm.maxnum.f32(float %a, float 2.0)
   %fmed = call float @llvm.minnum.f32(float %maxnum, float 4.0)
   ret float %fmed
 }
 
-define float @test_max_min_global_nnan(float %a) #2 {
+define float @test_max_min_global_nnan(float %a) {
 ; GFX10-LABEL: test_max_min_global_nnan:
 ; GFX10:       ; %bb.0:
 ; GFX10-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
@@ -281,8 +281,8 @@ define float @test_max_min_global_nnan(float %a) #2 {
 ; GFX12-NEXT:    s_wait_kmcnt 0x0
 ; GFX12-NEXT:    v_med3_num_f32 v0, v0, 2.0, 4.0
 ; GFX12-NEXT:    s_setpc_b64 s[30:31]
-  %minnum = call float @llvm.minnum.f32(float %a, float 4.0)
-  %fmed = call float @llvm.maxnum.f32(float %minnum, float 2.0)
+  %minnum = call nnan float @llvm.minnum.f32(float %a, float 4.0)
+  %fmed = call nnan float @llvm.maxnum.f32(float %minnum, float 2.0)
   ret float %fmed
 }
 
@@ -560,4 +560,3 @@ declare <2 x half> @llvm.minnum.v2f16(<2 x half>, <2 x half>)
 declare <2 x half> @llvm.maxnum.v2f16(<2 x half>, <2 x half>)
 attributes #0 = {"amdgpu-ieee"="true"}
 attributes #1 = {"amdgpu-ieee"="false"}
-attributes #2 = {"no-nans-fp-math"="true"}