[X86][SSE] SimplifyDemandedBitsForTargetNode - Add initial PACKSS support

RKSimon · RKSimon · commit 07adb6abdadf · 2019-04-07T10:40:01.000Z
In the case where we only want the sign bit (e.g. when using PACKSS truncation of comparison results for MOVMSK) then we can just demand the sign bit of the source operands. This makes use of the fact that PACKSS saturates out of range values to the min/max int values - so the sign bit is always preserved. Differential Revision: https://reviews.llvm.org/D60333 llvm-svn: 357859
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -33508,6 +33508,25 @@ bool X86TargetLowering::SimplifyDemandedBitsForTargetNode(
     }
     break;
   }
+  case X86ISD::PACKSS:
+    // PACKSS saturates to MIN/MAX integer values. So if we just want the
+    // sign bit then we can just ask for the source operands sign bit.
+    // TODO - add known bits handling.
+    if (OriginalDemandedBits.isSignMask()) {
+      APInt DemandedLHS, DemandedRHS;
+      getPackDemandedElts(VT, OriginalDemandedElts, DemandedLHS, DemandedRHS);
+
+      KnownBits KnownLHS, KnownRHS;
+      APInt SignMask = APInt::getSignMask(BitWidth * 2);
+      if (SimplifyDemandedBits(Op.getOperand(0), SignMask, DemandedLHS,
+                               KnownLHS, TLO, Depth + 1))
+        return true;
+      if (SimplifyDemandedBits(Op.getOperand(1), SignMask, DemandedRHS,
+                               KnownRHS, TLO, Depth + 1))
+        return true;
+    }
+    // TODO - add general PACKSS/PACKUS SimplifyDemandedBits support.
+    break;
   case X86ISD::PCMPGT:
     // icmp sgt(0, R) == ashr(R, BitWidth-1).
     // iff we only need the sign bit then we can use R directly.
diff --git a/llvm/test/CodeGen/X86/bitcast-and-setcc-512.ll b/llvm/test/CodeGen/X86/bitcast-and-setcc-512.ll
@@ -74,7 +74,6 @@ define i8 @v8i64(<8 x i64> %a, <8 x i64> %b, <8 x i64> %c, <8 x i64> %d) {
 ; AVX1-NEXT:    vpackssdw %xmm1, %xmm2, %xmm1
 ; AVX1-NEXT:    vpand %xmm1, %xmm0, %xmm0
 ; AVX1-NEXT:    vpsllw $15, %xmm0, %xmm0
-; AVX1-NEXT:    vpsraw $15, %xmm0, %xmm0
 ; AVX1-NEXT:    vpacksswb %xmm0, %xmm0, %xmm0
 ; AVX1-NEXT:    vpmovmskb %xmm0, %eax
 ; AVX1-NEXT:    # kill: def $al killed $al killed $eax
@@ -99,7 +98,6 @@ define i8 @v8i64(<8 x i64> %a, <8 x i64> %b, <8 x i64> %c, <8 x i64> %d) {
 ; AVX2-NEXT:    vpackssdw %xmm1, %xmm2, %xmm1
 ; AVX2-NEXT:    vpand %xmm1, %xmm0, %xmm0
 ; AVX2-NEXT:    vpsllw $15, %xmm0, %xmm0
-; AVX2-NEXT:    vpsraw $15, %xmm0, %xmm0
 ; AVX2-NEXT:    vpacksswb %xmm0, %xmm0, %xmm0
 ; AVX2-NEXT:    vpmovmskb %xmm0, %eax
 ; AVX2-NEXT:    # kill: def $al killed $al killed $eax
@@ -191,7 +189,6 @@ define i8 @v8f64(<8 x double> %a, <8 x double> %b, <8 x double> %c, <8 x double>
 ; AVX12-NEXT:    vpackssdw %xmm1, %xmm2, %xmm1
 ; AVX12-NEXT:    vpand %xmm1, %xmm0, %xmm0
 ; AVX12-NEXT:    vpsllw $15, %xmm0, %xmm0
-; AVX12-NEXT:    vpsraw $15, %xmm0, %xmm0
 ; AVX12-NEXT:    vpacksswb %xmm0, %xmm0, %xmm0
 ; AVX12-NEXT:    vpmovmskb %xmm0, %eax
 ; AVX12-NEXT:    # kill: def $al killed $al killed $eax
diff --git a/llvm/test/CodeGen/X86/bitcast-setcc-128.ll b/llvm/test/CodeGen/X86/bitcast-setcc-128.ll
@@ -765,17 +765,13 @@ define void @bitcast_16i8_store(i16* %p, <16 x i8> %a0) {
 define void @bitcast_8i16_store(i8* %p, <8 x i16> %a0) {
 ; SSE2-SSSE3-LABEL: bitcast_8i16_store:
 ; SSE2-SSSE3:       # %bb.0:
-; SSE2-SSSE3-NEXT:    pxor %xmm1, %xmm1
-; SSE2-SSSE3-NEXT:    pcmpgtw %xmm0, %xmm1
-; SSE2-SSSE3-NEXT:    packsswb %xmm0, %xmm1
-; SSE2-SSSE3-NEXT:    pmovmskb %xmm1, %eax
+; SSE2-SSSE3-NEXT:    packsswb %xmm0, %xmm0
+; SSE2-SSSE3-NEXT:    pmovmskb %xmm0, %eax
 ; SSE2-SSSE3-NEXT:    movb %al, (%rdi)
 ; SSE2-SSSE3-NEXT:    retq
 ;
 ; AVX12-LABEL: bitcast_8i16_store:
 ; AVX12:       # %bb.0:
-; AVX12-NEXT:    vpxor %xmm1, %xmm1, %xmm1
-; AVX12-NEXT:    vpcmpgtw %xmm0, %xmm1, %xmm0
 ; AVX12-NEXT:    vpacksswb %xmm0, %xmm0, %xmm0
 ; AVX12-NEXT:    vpmovmskb %xmm0, %eax
 ; AVX12-NEXT:    movb %al, (%rdi)
diff --git a/llvm/test/CodeGen/X86/bitcast-setcc-256.ll b/llvm/test/CodeGen/X86/bitcast-setcc-256.ll
@@ -359,21 +359,14 @@ define void @bitcast_32i8_store(i32* %p, <32 x i8> %a0) {
 define void @bitcast_16i16_store(i16* %p, <16 x i16> %a0) {
 ; SSE2-SSSE3-LABEL: bitcast_16i16_store:
 ; SSE2-SSSE3:       # %bb.0:
-; SSE2-SSSE3-NEXT:    pxor %xmm2, %xmm2
-; SSE2-SSSE3-NEXT:    pxor %xmm3, %xmm3
-; SSE2-SSSE3-NEXT:    pcmpgtw %xmm1, %xmm3
-; SSE2-SSSE3-NEXT:    pcmpgtw %xmm0, %xmm2
-; SSE2-SSSE3-NEXT:    packsswb %xmm3, %xmm2
-; SSE2-SSSE3-NEXT:    pmovmskb %xmm2, %eax
+; SSE2-SSSE3-NEXT:    packsswb %xmm1, %xmm0
+; SSE2-SSSE3-NEXT:    pmovmskb %xmm0, %eax
 ; SSE2-SSSE3-NEXT:    movw %ax, (%rdi)
 ; SSE2-SSSE3-NEXT:    retq
 ;
 ; AVX1-LABEL: bitcast_16i16_store:
 ; AVX1:       # %bb.0:
 ; AVX1-NEXT:    vextractf128 $1, %ymm0, %xmm1
-; AVX1-NEXT:    vpxor %xmm2, %xmm2, %xmm2
-; AVX1-NEXT:    vpcmpgtw %xmm1, %xmm2, %xmm1
-; AVX1-NEXT:    vpcmpgtw %xmm0, %xmm2, %xmm0
 ; AVX1-NEXT:    vpacksswb %xmm1, %xmm0, %xmm0
 ; AVX1-NEXT:    vpmovmskb %xmm0, %eax
 ; AVX1-NEXT:    movw %ax, (%rdi)
@@ -416,13 +409,9 @@ define void @bitcast_16i16_store(i16* %p, <16 x i16> %a0) {
 define void @bitcast_8i32_store(i8* %p, <8 x i32> %a0) {
 ; SSE2-SSSE3-LABEL: bitcast_8i32_store:
 ; SSE2-SSSE3:       # %bb.0:
-; SSE2-SSSE3-NEXT:    pxor %xmm2, %xmm2
-; SSE2-SSSE3-NEXT:    pxor %xmm3, %xmm3
-; SSE2-SSSE3-NEXT:    pcmpgtd %xmm1, %xmm3
-; SSE2-SSSE3-NEXT:    pcmpgtd %xmm0, %xmm2
-; SSE2-SSSE3-NEXT:    packssdw %xmm3, %xmm2
-; SSE2-SSSE3-NEXT:    packsswb %xmm0, %xmm2
-; SSE2-SSSE3-NEXT:    pmovmskb %xmm2, %eax
+; SSE2-SSSE3-NEXT:    packssdw %xmm1, %xmm0
+; SSE2-SSSE3-NEXT:    packsswb %xmm0, %xmm0
+; SSE2-SSSE3-NEXT:    pmovmskb %xmm0, %eax
 ; SSE2-SSSE3-NEXT:    movb %al, (%rdi)
 ; SSE2-SSSE3-NEXT:    retq
 ;
diff --git a/llvm/test/CodeGen/X86/bitcast-setcc-512.ll b/llvm/test/CodeGen/X86/bitcast-setcc-512.ll
@@ -481,18 +481,10 @@ define void @bitcast_64i8_store(i64* %p, <64 x i8> %a0) {
 define void @bitcast_32i16_store(i32* %p, <32 x i16> %a0) {
 ; SSE-LABEL: bitcast_32i16_store:
 ; SSE:       # %bb.0:
-; SSE-NEXT:    pxor %xmm4, %xmm4
-; SSE-NEXT:    pxor %xmm5, %xmm5
-; SSE-NEXT:    pcmpgtw %xmm1, %xmm5
-; SSE-NEXT:    pxor %xmm1, %xmm1
-; SSE-NEXT:    pcmpgtw %xmm0, %xmm1
-; SSE-NEXT:    packsswb %xmm5, %xmm1
-; SSE-NEXT:    pmovmskb %xmm1, %eax
-; SSE-NEXT:    pxor %xmm0, %xmm0
-; SSE-NEXT:    pcmpgtw %xmm3, %xmm0
-; SSE-NEXT:    pcmpgtw %xmm2, %xmm4
-; SSE-NEXT:    packsswb %xmm0, %xmm4
-; SSE-NEXT:    pmovmskb %xmm4, %ecx
+; SSE-NEXT:    packsswb %xmm1, %xmm0
+; SSE-NEXT:    pmovmskb %xmm0, %eax
+; SSE-NEXT:    packsswb %xmm3, %xmm2
+; SSE-NEXT:    pmovmskb %xmm2, %ecx
 ; SSE-NEXT:    shll $16, %ecx
 ; SSE-NEXT:    orl %eax, %ecx
 ; SSE-NEXT:    movl %ecx, (%rdi)
@@ -501,14 +493,9 @@ define void @bitcast_32i16_store(i32* %p, <32 x i16> %a0) {
 ; AVX1-LABEL: bitcast_32i16_store:
 ; AVX1:       # %bb.0:
 ; AVX1-NEXT:    vextractf128 $1, %ymm0, %xmm2
-; AVX1-NEXT:    vpxor %xmm3, %xmm3, %xmm3
-; AVX1-NEXT:    vpcmpgtw %xmm2, %xmm3, %xmm2
-; AVX1-NEXT:    vpcmpgtw %xmm0, %xmm3, %xmm0
 ; AVX1-NEXT:    vpacksswb %xmm2, %xmm0, %xmm0
 ; AVX1-NEXT:    vpmovmskb %xmm0, %eax
 ; AVX1-NEXT:    vextractf128 $1, %ymm1, %xmm0
-; AVX1-NEXT:    vpcmpgtw %xmm0, %xmm3, %xmm0
-; AVX1-NEXT:    vpcmpgtw %xmm1, %xmm3, %xmm1
 ; AVX1-NEXT:    vpacksswb %xmm0, %xmm1, %xmm0
 ; AVX1-NEXT:    vpmovmskb %xmm0, %ecx
 ; AVX1-NEXT:    shll $16, %ecx
@@ -519,9 +506,6 @@ define void @bitcast_32i16_store(i32* %p, <32 x i16> %a0) {
 ;
 ; AVX2-LABEL: bitcast_32i16_store:
 ; AVX2:       # %bb.0:
-; AVX2-NEXT:    vpxor %xmm2, %xmm2, %xmm2
-; AVX2-NEXT:    vpcmpgtw %ymm1, %ymm2, %ymm1
-; AVX2-NEXT:    vpcmpgtw %ymm0, %ymm2, %ymm0
 ; AVX2-NEXT:    vpacksswb %ymm1, %ymm0, %ymm0
 ; AVX2-NEXT:    vpermq {{.*#+}} ymm0 = ymm0[0,2,1,3]
 ; AVX2-NEXT:    vpmovmskb %ymm0, %eax
@@ -558,31 +542,18 @@ define void @bitcast_32i16_store(i32* %p, <32 x i16> %a0) {
 define void @bitcast_16i32_store(i16* %p, <16 x i32> %a0) {
 ; SSE-LABEL: bitcast_16i32_store:
 ; SSE:       # %bb.0:
-; SSE-NEXT:    pxor %xmm4, %xmm4
-; SSE-NEXT:    pxor %xmm5, %xmm5
-; SSE-NEXT:    pcmpgtd %xmm3, %xmm5
-; SSE-NEXT:    pxor %xmm3, %xmm3
-; SSE-NEXT:    pcmpgtd %xmm2, %xmm3
-; SSE-NEXT:    packssdw %xmm5, %xmm3
-; SSE-NEXT:    pxor %xmm2, %xmm2
-; SSE-NEXT:    pcmpgtd %xmm1, %xmm2
-; SSE-NEXT:    pcmpgtd %xmm0, %xmm4
-; SSE-NEXT:    packssdw %xmm2, %xmm4
-; SSE-NEXT:    packsswb %xmm3, %xmm4
-; SSE-NEXT:    pmovmskb %xmm4, %eax
+; SSE-NEXT:    packssdw %xmm3, %xmm2
+; SSE-NEXT:    packssdw %xmm1, %xmm0
+; SSE-NEXT:    packsswb %xmm2, %xmm0
+; SSE-NEXT:    pmovmskb %xmm0, %eax
 ; SSE-NEXT:    movw %ax, (%rdi)
 ; SSE-NEXT:    retq
 ;
 ; AVX1-LABEL: bitcast_16i32_store:
 ; AVX1:       # %bb.0:
 ; AVX1-NEXT:    vextractf128 $1, %ymm1, %xmm2
-; AVX1-NEXT:    vpxor %xmm3, %xmm3, %xmm3
-; AVX1-NEXT:    vpcmpgtd %xmm2, %xmm3, %xmm2
-; AVX1-NEXT:    vpcmpgtd %xmm1, %xmm3, %xmm1
 ; AVX1-NEXT:    vpackssdw %xmm2, %xmm1, %xmm1
 ; AVX1-NEXT:    vextractf128 $1, %ymm0, %xmm2
-; AVX1-NEXT:    vpcmpgtd %xmm2, %xmm3, %xmm2
-; AVX1-NEXT:    vpcmpgtd %xmm0, %xmm3, %xmm0
 ; AVX1-NEXT:    vpackssdw %xmm2, %xmm0, %xmm0
 ; AVX1-NEXT:    vpacksswb %xmm1, %xmm0, %xmm0
 ; AVX1-NEXT:    vpmovmskb %xmm0, %eax
diff --git a/llvm/test/CodeGen/X86/movmsk-cmp.ll b/llvm/test/CodeGen/X86/movmsk-cmp.ll
