[X86 Codegen] Fixed a bug in unsigned saturation

PACKUSWB converts Signed word to Unsigned byte, (the same about DW) and it can't be used for umin+truncate pattern.
AVX-512 VPMOVUS* instructions fit the pattern since they convert Unsigned to Unsigned.

See https://llvm.org/bugs/show_bug.cgi?id=31773

Differential Revision: https://reviews.llvm.org/D29196

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293431 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 1d0cefc321411317e37c74e11af2d6bd160c9487..2de2d53160311530684b2d03318c99c319f94c0c 100644 (file)
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -31382,21 +31382,6 @@ static bool isSATValidOnAVX512Subtarget(EVT SrcVT, EVT DstVT,
   return false;
 }
 
-/// Return true if VPACK* instruction can be used for the given types
-/// and it is avalable on \p Subtarget.
-static bool
-isSATValidOnSSESubtarget(EVT SrcVT, EVT DstVT, const X86Subtarget &Subtarget) {
-  if (Subtarget.hasSSE2())
-    // v16i16 -> v16i8
-    if (SrcVT == MVT::v16i16 && DstVT == MVT::v16i8)
-      return true;
-  if (Subtarget.hasSSE41())
-    // v8i32 -> v8i16
-    if (SrcVT == MVT::v8i32 && DstVT == MVT::v8i16)
-      return true;
-  return false;
-}
-
 /// Detect a pattern of truncation with saturation:
 /// (truncate (umin (x, unsigned_max_of_dest_type)) to dest_type).
 /// Return the source value to be truncated or SDValue() if the pattern was not
@@ -31437,16 +31422,9 @@ combineTruncateWithUSat(SDValue In, EVT VT, SDLoc &DL, SelectionDAG &DAG,
   const TargetLowering &TLI = DAG.getTargetLoweringInfo();
   if (!TLI.isTypeLegal(In.getValueType()) || !TLI.isTypeLegal(VT))
     return SDValue();
-  SDValue USatVal = detectUSatPattern(In, VT);
-  if (USatVal) {
+  if (auto USatVal = detectUSatPattern(In, VT))
     if (isSATValidOnAVX512Subtarget(In.getValueType(), VT, Subtarget))
       return DAG.getNode(X86ISD::VTRUNCUS, DL, VT, USatVal);
-    if (isSATValidOnSSESubtarget(In.getValueType(), VT, Subtarget)) {
-      SDValue Lo, Hi;
-      std::tie(Lo, Hi) = DAG.SplitVector(USatVal, DL);
-      return DAG.getNode(X86ISD::PACKUS, DL, VT, Lo, Hi);
-    }
-  }
   return SDValue();
 }
 

diff --git a/test/CodeGen/X86/avx-trunc.ll b/test/CodeGen/X86/avx-trunc.ll
index c729b988cfb8bf21bd0fd09ab2241d330c206dcb..1a9acd007778e3eb1cbe240bad37cb77eea888e7 100644 (file)
--- a/test/CodeGen/X86/avx-trunc.ll
+++ b/test/CodeGen/X86/avx-trunc.ll
@@ -40,28 +40,4 @@ define <16 x i8> @trunc_16_8(<16 x i16> %A) nounwind uwtable readnone ssp{
   ret <16 x i8> %B
 }
 
-define <16 x i8> @usat_trunc_wb_256(<16 x i16> %i) {
-; CHECK-LABEL: usat_trunc_wb_256:
-; CHECK:       # BB#0:
-; CHECK-NEXT:    vextractf128 $1, %ymm0, %xmm1
-; CHECK-NEXT:    vpackuswb %xmm1, %xmm0, %xmm0
-; CHECK-NEXT:    vzeroupper
-; CHECK-NEXT:    retq
-  %x3 = icmp ult <16 x i16> %i, <i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255>
-  %x5 = select <16 x i1> %x3, <16 x i16> %i, <16 x i16> <i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255>
-  %x6 = trunc <16 x i16> %x5 to <16 x i8>
-  ret <16 x i8> %x6
-}
 
-define <8 x i16> @usat_trunc_dw_256(<8 x i32> %i) {
-; CHECK-LABEL: usat_trunc_dw_256:
-; CHECK:       # BB#0:
-; CHECK-NEXT:    vextractf128 $1, %ymm0, %xmm1
-; CHECK-NEXT:    vpackusdw %xmm1, %xmm0, %xmm0
-; CHECK-NEXT:    vzeroupper
-; CHECK-NEXT:    retq
-  %x3 = icmp ult <8 x i32> %i, <i32 65535, i32 65535, i32 65535, i32 65535, i32 65535, i32 65535, i32 65535, i32 65535>
-  %x5 = select <8 x i1> %x3, <8 x i32> %i, <8 x i32> <i32 65535, i32 65535, i32 65535, i32 65535, i32 65535, i32 65535, i32 65535, i32 65535>
-  %x6 = trunc <8 x i32> %x5 to <8 x i16>
-  ret <8 x i16> %x6
-}

diff --git a/test/CodeGen/X86/avx512-trunc.ll b/test/CodeGen/X86/avx512-trunc.ll
index 85e607c4be754c4e7eb00daa689aa19682f098d1..ac58024772b49c8c18e3444ee8dc31af00e89759 100644 (file)
--- a/test/CodeGen/X86/avx512-trunc.ll
+++ b/test/CodeGen/X86/avx512-trunc.ll
@@ -505,8 +505,9 @@ define void @trunc_wb_128_mem(<8 x i16> %i, <8 x i8>* %res) #0 {
 define void @usat_trunc_wb_256_mem(<16 x i16> %i, <16 x i8>* %res) {
 ; KNL-LABEL: usat_trunc_wb_256_mem:
 ; KNL:       ## BB#0:
-; KNL-NEXT:    vextracti128 $1, %ymm0, %xmm1
-; KNL-NEXT:    vpackuswb %xmm1, %xmm0, %xmm0
+; KNL-NEXT:    vpminuw {{.*}}(%rip), %ymm0, %ymm0
+; KNL-NEXT:    vpmovsxwd %ymm0, %zmm0
+; KNL-NEXT:    vpmovdb %zmm0, %xmm0
 ; KNL-NEXT:    vmovdqu %xmm0, (%rdi)
 ; KNL-NEXT:    retq
 ;
@@ -524,8 +525,9 @@ define void @usat_trunc_wb_256_mem(<16 x i16> %i, <16 x i8>* %res) {
 define <16 x i8> @usat_trunc_wb_256(<16 x i16> %i) {
 ; KNL-LABEL: usat_trunc_wb_256:
 ; KNL:       ## BB#0:
-; KNL-NEXT:    vextracti128 $1, %ymm0, %xmm1
-; KNL-NEXT:    vpackuswb %xmm1, %xmm0, %xmm0
+; KNL-NEXT:    vpminuw {{.*}}(%rip), %ymm0, %ymm0
+; KNL-NEXT:    vpmovsxwd %ymm0, %zmm0
+; KNL-NEXT:    vpmovdb %zmm0, %xmm0
 ; KNL-NEXT:    retq
 ;
 ; SKX-LABEL: usat_trunc_wb_256:

diff --git a/test/CodeGen/X86/pr31773.ll b/test/CodeGen/X86/pr31773.ll
new file mode 100644 (file)
index 0000000..8722df3
--- /dev/null
+++ b/test/CodeGen/X86/pr31773.ll
@@ -0,0 +1,20 @@
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=+avx | FileCheck %s
+
+; This matter of this test is ensuring that vpackus* is not used for umin+trunc combination, since vpackus* input is a signed number.
+define <16 x i8> @usat_trunc_wb_256(<16 x i16> %i) {
+; CHECK-LABEL: usat_trunc_wb_256:
+; CHECK-NOT:    vpackuswb %xmm1, %xmm0, %xmm0
+  %x3 = icmp ult <16 x i16> %i, <i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255>
+  %x5 = select <16 x i1> %x3, <16 x i16> %i, <16 x i16> <i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255, i16 255>
+  %x6 = trunc <16 x i16> %x5 to <16 x i8>
+  ret <16 x i8> %x6
+}
+ 
+define <8 x i16> @usat_trunc_dw_256(<8 x i32> %i) {
+; CHECK-LABEL: usat_trunc_dw_256:
+; CHECK-NOT:    vpackusdw %xmm1, %xmm0, %xmm0
+  %x3 = icmp ult <8 x i32> %i, <i32 65535, i32 65535, i32 65535, i32 65535, i32 65535, i32 65535, i32 65535, i32 65535>
+  %x5 = select <8 x i1> %x3, <8 x i32> %i, <8 x i32> <i32 65535, i32 65535, i32 65535, i32 65535, i32 65535, i32 65535, i32 65535, i32 65535>
+  %x6 = trunc <8 x i32> %x5 to <8 x i16>
+  ret <8 x i16> %x6
+}