[PATCH] D45219: [AMDGPU] performMinMaxCombine should not optimize patterns of vectors to min3/max3

[Farhana Aleen via Phabricator via llvm-commits]

FarhanaAleen created this revision.
FarhanaAleen added a reviewer: rampitec.
Herald added subscribers: t-tye, tpr, dstuttard, yaxunl, nhaehnle, wdng, kzhuravl, arsenm.

There are no packed instructions for min3 or max3. So, performMinMaxCombine should not optimize vectors of f16 to min3/max3.


https://reviews.llvm.org/D45219

Files:
  lib/Target/AMDGPU/SIISelLowering.cpp
  test/CodeGen/AMDGPU/fmax3.ll
  test/CodeGen/AMDGPU/fmin3.ll


Index: test/CodeGen/AMDGPU/fmin3.ll
===================================================================
--- test/CodeGen/AMDGPU/fmin3.ll
+++ test/CodeGen/AMDGPU/fmin3.ll
@@ -82,9 +82,20 @@
   ret void
 }
 
+; Checks whether the test passes; performMinMaxCombine() should not optimize vector patterns of min3
+; since there are no pack instructions for fmin3.
+define <2 x half> @no_fmin3_v2f16(<2 x half> %a, <2 x half> %b, <2 x half> %c, <2 x half> %d) {
+entry:
+  %min = tail call fast <2 x half> @llvm.minnum.v2f16(<2 x half> %a, <2 x half> %b)
+  %min1 = tail call fast <2 x half> @llvm.minnum.v2f16(<2 x half> %c, <2 x half> %min)
+  %res = tail call fast <2 x half> @llvm.minnum.v2f16(<2 x half> %min1, <2 x half> %d)
+  ret <2 x half> %res
+}
+
 declare i32 @llvm.amdgcn.workitem.id.x() #1
 declare float @llvm.minnum.f32(float, float) #1
 declare half @llvm.minnum.f16(half, half) #1
+declare <2 x half> @llvm.minnum.v2f16(<2 x half>, <2 x half>)
 
 attributes #0 = { nounwind }
 attributes #1 = { nounwind readnone speculatable }
Index: test/CodeGen/AMDGPU/fmax3.ll
===================================================================
--- test/CodeGen/AMDGPU/fmax3.ll
+++ test/CodeGen/AMDGPU/fmax3.ll
@@ -84,9 +84,20 @@
   ret void
 }
 
+; Checks whether the test passes; performMinMaxCombine() should not optimize vector patterns of max3
+; since there are no pack instructions for fmax3.
+define <2 x half> @no_fmax3_v2f16(<2 x half> %a, <2 x half> %b, <2 x half> %c, <2 x half> %d) {
+entry:
+  %max = tail call fast <2 x half> @llvm.maxnum.v2f16(<2 x half> %a, <2 x half> %b)
+  %max1 = tail call fast <2 x half> @llvm.maxnum.v2f16(<2 x half> %c, <2 x half> %max)
+  %res = tail call fast <2 x half> @llvm.maxnum.v2f16(<2 x half> %max1, <2 x half> %d)
+  ret <2 x half> %res
+}
+
 declare i32 @llvm.amdgcn.workitem.id.x() #1
 declare float @llvm.maxnum.f32(float, float) #1
 declare half @llvm.maxnum.f16(half, half) #1
+declare <2 x half> @llvm.maxnum.v2f16(<2 x half>, <2 x half>)
 
 attributes #0 = { nounwind }
 attributes #1 = { nounwind readnone speculatable }
Index: lib/Target/AMDGPU/SIISelLowering.cpp
===================================================================
--- lib/Target/AMDGPU/SIISelLowering.cpp
+++ lib/Target/AMDGPU/SIISelLowering.cpp
@@ -6446,7 +6446,7 @@
 
 
   if (Opc != AMDGPUISD::FMIN_LEGACY && Opc != AMDGPUISD::FMAX_LEGACY &&
-      VT != MVT::f64 &&
+      !VT.isVector() && VT != MVT::f64 &&
       ((VT != MVT::f16 && VT != MVT::i16) || Subtarget->hasMin3Max3_16())) {
     // max(max(a, b), c) -> max3(a, b, c)
     // min(min(a, b), c) -> min3(a, b, c)


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