AMDGPU: Combine nnan fminimum/fmaximum to fminnum_ieee/fmaxnum_ieee (#142217)

This improves codegen for gfx950, where fminimum/fmaximum are
legal through fminimum3/fmaximum3, so may have an additional
encoding cost.

Author: arsenm

llvm/lib/Target/AMDGPU/SIISelLowering.cpp

@@ -13880,6 +13880,17 @@ SDValue SITargetLowering::performMinMaxCombine(SDNode *N,
       return Res;
   }
 
+  // Prefer fminnum_ieee over fminimum. For gfx950, minimum/maximum are legal
+  // for some types, but at a higher cost since it's implemented with a 3
+  // operand form.
+  const SDNodeFlags Flags = N->getFlags();
+  if ((Opc == ISD::FMINIMUM || Opc == ISD::FMAXIMUM) &&
+      !Subtarget->hasIEEEMinMax() && Flags.hasNoNaNs()) {
+    unsigned NewOpc =
+        Opc == ISD::FMINIMUM ? ISD::FMINNUM_IEEE : ISD::FMAXNUM_IEEE;
+    return DAG.getNode(NewOpc, SDLoc(N), VT, Op0, Op1, Flags);
+  }
+
   return SDValue();
 }
 

llvm/test/CodeGen/AMDGPU/llvm.maximum.f16.ll

@@ -113,17 +113,11 @@ define half @v_maximum_f16__nnan(half %src0, half %src1) {
 ; GFX8-NEXT:    v_max_f16_e32 v0, v0, v1
 ; GFX8-NEXT:    s_setpc_b64 s[30:31]
 ;
-; GFX900-LABEL: v_maximum_f16__nnan:
-; GFX900:       ; %bb.0:
-; GFX900-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; GFX900-NEXT:    v_max_f16_e32 v0, v0, v1
-; GFX900-NEXT:    s_setpc_b64 s[30:31]
-;
-; GFX950-LABEL: v_maximum_f16__nnan:
-; GFX950:       ; %bb.0:
-; GFX950-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; GFX950-NEXT:    v_pk_maximum3_f16 v0, v0, v1, v1
-; GFX950-NEXT:    s_setpc_b64 s[30:31]
+; GFX9-LABEL: v_maximum_f16__nnan:
+; GFX9:       ; %bb.0:
+; GFX9-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; GFX9-NEXT:    v_max_f16_e32 v0, v0, v1
+; GFX9-NEXT:    s_setpc_b64 s[30:31]
 ;
 ; GFX10-LABEL: v_maximum_f16__nnan:
 ; GFX10:       ; %bb.0:
@@ -270,17 +264,11 @@ define half @v_maximum_f16__nnan_nsz(half %src0, half %src1) {
 ; GFX8-NEXT:    v_max_f16_e32 v0, v0, v1
 ; GFX8-NEXT:    s_setpc_b64 s[30:31]
 ;
-; GFX900-LABEL: v_maximum_f16__nnan_nsz:
-; GFX900:       ; %bb.0:
-; GFX900-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; GFX900-NEXT:    v_max_f16_e32 v0, v0, v1
-; GFX900-NEXT:    s_setpc_b64 s[30:31]
-;
-; GFX950-LABEL: v_maximum_f16__nnan_nsz:
-; GFX950:       ; %bb.0:
-; GFX950-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; GFX950-NEXT:    v_pk_maximum3_f16 v0, v0, v1, v1
-; GFX950-NEXT:    s_setpc_b64 s[30:31]
+; GFX9-LABEL: v_maximum_f16__nnan_nsz:
+; GFX9:       ; %bb.0:
+; GFX9-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; GFX9-NEXT:    v_max_f16_e32 v0, v0, v1
+; GFX9-NEXT:    s_setpc_b64 s[30:31]
 ;
 ; GFX10-LABEL: v_maximum_f16__nnan_nsz:
 ; GFX10:       ; %bb.0:
@@ -771,17 +759,11 @@ define <2 x half> @v_maximum_v2f16__nnan(<2 x half> %src0, <2 x half> %src1) {
 ; GFX8-NEXT:    v_or_b32_e32 v0, v0, v2
 ; GFX8-NEXT:    s_setpc_b64 s[30:31]
 ;
-; GFX900-LABEL: v_maximum_v2f16__nnan:
-; GFX900:       ; %bb.0:
-; GFX900-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; GFX900-NEXT:    v_pk_max_f16 v0, v0, v1
-; GFX900-NEXT:    s_setpc_b64 s[30:31]
-;
-; GFX950-LABEL: v_maximum_v2f16__nnan:
-; GFX950:       ; %bb.0:
-; GFX950-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; GFX950-NEXT:    v_pk_maximum3_f16 v0, v0, v1, v1
-; GFX950-NEXT:    s_setpc_b64 s[30:31]
+; GFX9-LABEL: v_maximum_v2f16__nnan:
+; GFX9:       ; %bb.0:
+; GFX9-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; GFX9-NEXT:    v_pk_max_f16 v0, v0, v1
+; GFX9-NEXT:    s_setpc_b64 s[30:31]
 ;
 ; GFX10-LABEL: v_maximum_v2f16__nnan:
 ; GFX10:       ; %bb.0:
@@ -939,17 +921,11 @@ define <2 x half> @v_maximum_v2f16__nnan_nsz(<2 x half> %src0, <2 x half> %src1)
 ; GFX8-NEXT:    v_or_b32_e32 v0, v0, v2
 ; GFX8-NEXT:    s_setpc_b64 s[30:31]
 ;
-; GFX900-LABEL: v_maximum_v2f16__nnan_nsz:
-; GFX900:       ; %bb.0:
-; GFX900-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; GFX900-NEXT:    v_pk_max_f16 v0, v0, v1
-; GFX900-NEXT:    s_setpc_b64 s[30:31]
-;
-; GFX950-LABEL: v_maximum_v2f16__nnan_nsz:
-; GFX950:       ; %bb.0:
-; GFX950-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; GFX950-NEXT:    v_pk_maximum3_f16 v0, v0, v1, v1
-; GFX950-NEXT:    s_setpc_b64 s[30:31]
+; GFX9-LABEL: v_maximum_v2f16__nnan_nsz:
+; GFX9:       ; %bb.0:
+; GFX9-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; GFX9-NEXT:    v_pk_max_f16 v0, v0, v1
+; GFX9-NEXT:    s_setpc_b64 s[30:31]
 ;
 ; GFX10-LABEL: v_maximum_v2f16__nnan_nsz:
 ; GFX10:       ; %bb.0:
@@ -1296,19 +1272,12 @@ define <3 x half> @v_maximum_v3f16__nnan(<3 x half> %src0, <3 x half> %src1) {
 ; GFX8-NEXT:    v_or_b32_e32 v0, v0, v4
 ; GFX8-NEXT:    s_setpc_b64 s[30:31]
 ;
-; GFX900-LABEL: v_maximum_v3f16__nnan:
-; GFX900:       ; %bb.0:
-; GFX900-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; GFX900-NEXT:    v_pk_max_f16 v0, v0, v2
-; GFX900-NEXT:    v_pk_max_f16 v1, v1, v3
-; GFX900-NEXT:    s_setpc_b64 s[30:31]
-;
-; GFX950-LABEL: v_maximum_v3f16__nnan:
-; GFX950:       ; %bb.0:
-; GFX950-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; GFX950-NEXT:    v_pk_maximum3_f16 v1, v1, v3, v3
-; GFX950-NEXT:    v_pk_maximum3_f16 v0, v0, v2, v2
-; GFX950-NEXT:    s_setpc_b64 s[30:31]
+; GFX9-LABEL: v_maximum_v3f16__nnan:
+; GFX9:       ; %bb.0:
+; GFX9-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; GFX9-NEXT:    v_pk_max_f16 v1, v1, v3
+; GFX9-NEXT:    v_pk_max_f16 v0, v0, v2
+; GFX9-NEXT:    s_setpc_b64 s[30:31]
 ;
 ; GFX10-LABEL: v_maximum_v3f16__nnan:
 ; GFX10:       ; %bb.0:
@@ -1501,19 +1470,12 @@ define <3 x half> @v_maximum_v3f16__nnan_nsz(<3 x half> %src0, <3 x half> %src1)
 ; GFX8-NEXT:    v_or_b32_e32 v0, v0, v4
 ; GFX8-NEXT:    s_setpc_b64 s[30:31]
 ;
-; GFX900-LABEL: v_maximum_v3f16__nnan_nsz:
-; GFX900:       ; %bb.0:
-; GFX900-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; GFX900-NEXT:    v_pk_max_f16 v0, v0, v2
-; GFX900-NEXT:    v_pk_max_f16 v1, v1, v3
-; GFX900-NEXT:    s_setpc_b64 s[30:31]
-;
-; GFX950-LABEL: v_maximum_v3f16__nnan_nsz:
-; GFX950:       ; %bb.0:
-; GFX950-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; GFX950-NEXT:    v_pk_maximum3_f16 v1, v1, v3, v3
-; GFX950-NEXT:    v_pk_maximum3_f16 v0, v0, v2, v2
-; GFX950-NEXT:    s_setpc_b64 s[30:31]
+; GFX9-LABEL: v_maximum_v3f16__nnan_nsz:
+; GFX9:       ; %bb.0:
+; GFX9-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; GFX9-NEXT:    v_pk_max_f16 v1, v1, v3
+; GFX9-NEXT:    v_pk_max_f16 v0, v0, v2
+; GFX9-NEXT:    s_setpc_b64 s[30:31]
 ;
 ; GFX10-LABEL: v_maximum_v3f16__nnan_nsz:
 ; GFX10:       ; %bb.0:
@@ -1741,19 +1703,12 @@ define <4 x half> @v_maximum_v4f16__nnan(<4 x half> %src0, <4 x half> %src1) {
 ; GFX8-NEXT:    v_or_b32_e32 v1, v1, v4
 ; GFX8-NEXT:    s_setpc_b64 s[30:31]
 ;
-; GFX900-LABEL: v_maximum_v4f16__nnan:
-; GFX900:       ; %bb.0:
-; GFX900-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; GFX900-NEXT:    v_pk_max_f16 v0, v0, v2
-; GFX900-NEXT:    v_pk_max_f16 v1, v1, v3
-; GFX900-NEXT:    s_setpc_b64 s[30:31]
-;
-; GFX950-LABEL: v_maximum_v4f16__nnan:
-; GFX950:       ; %bb.0:
-; GFX950-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; GFX950-NEXT:    v_pk_maximum3_f16 v0, v0, v2, v2
-; GFX950-NEXT:    v_pk_maximum3_f16 v1, v1, v3, v3
-; GFX950-NEXT:    s_setpc_b64 s[30:31]
+; GFX9-LABEL: v_maximum_v4f16__nnan:
+; GFX9:       ; %bb.0:
+; GFX9-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; GFX9-NEXT:    v_pk_max_f16 v0, v0, v2
+; GFX9-NEXT:    v_pk_max_f16 v1, v1, v3
+; GFX9-NEXT:    s_setpc_b64 s[30:31]
 ;
 ; GFX10-LABEL: v_maximum_v4f16__nnan:
 ; GFX10:       ; %bb.0:
@@ -1981,19 +1936,12 @@ define <4 x half> @v_maximum_v4f16__nnan_nsz(<4 x half> %src0, <4 x half> %src1)
 ; GFX8-NEXT:    v_or_b32_e32 v1, v1, v4
 ; GFX8-NEXT:    s_setpc_b64 s[30:31]
 ;
-; GFX900-LABEL: v_maximum_v4f16__nnan_nsz:
-; GFX900:       ; %bb.0:
-; GFX900-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; GFX900-NEXT:    v_pk_max_f16 v0, v0, v2
-; GFX900-NEXT:    v_pk_max_f16 v1, v1, v3
-; GFX900-NEXT:    s_setpc_b64 s[30:31]
-;
-; GFX950-LABEL: v_maximum_v4f16__nnan_nsz:
-; GFX950:       ; %bb.0:
-; GFX950-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; GFX950-NEXT:    v_pk_maximum3_f16 v0, v0, v2, v2
-; GFX950-NEXT:    v_pk_maximum3_f16 v1, v1, v3, v3
-; GFX950-NEXT:    s_setpc_b64 s[30:31]
+; GFX9-LABEL: v_maximum_v4f16__nnan_nsz:
+; GFX9:       ; %bb.0:
+; GFX9-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; GFX9-NEXT:    v_pk_max_f16 v0, v0, v2
+; GFX9-NEXT:    v_pk_max_f16 v1, v1, v3
+; GFX9-NEXT:    s_setpc_b64 s[30:31]
 ;
 ; GFX10-LABEL: v_maximum_v4f16__nnan_nsz:
 ; GFX10:       ; %bb.0:
@@ -2788,4 +2736,3 @@ define <16 x half> @v_maximum_v16f16(<16 x half> %src0, <16 x half> %src1) {
 }
 ;; NOTE: These prefixes are unused and the list is autogenerated. Do not add tests below this line:
 ; GCN: {{.*}}
-; GFX9: {{.*}}