[llvm] [DAG] foldABSToABD - support abs(*ext(x) - *ext(y)) -> zext(abd*(x, y)) from different extension source types (PR #71670)

Simon Pilgrim via llvm-commits llvm-commits at lists.llvm.org
Tue Nov 14 02:18:46 PST 2023


https://github.com/RKSimon updated https://github.com/llvm/llvm-project/pull/71670

>From 35a4e15158fe6204d958fcbc4ceadbf1683fdf4f Mon Sep 17 00:00:00 2001
From: Simon Pilgrim <llvm-dev at redking.me.uk>
Date: Wed, 8 Nov 2023 12:21:01 +0000
Subject: [PATCH] [DAG] foldABSToABD - support abs(*ext(x) - *ext(y)) ->
 zext(abd*(x, y)) from different extension source types

We currently limit the fold to cases where we're extending from the same source type, but we can safely perform this using the wider of mismatching source types (we're really just interested in having extension bits on both sources), ensuring we don't create additional extensions/truncations.
---
 llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 11 +--
 llvm/test/CodeGen/AArch64/sve-abd.ll          | 12 +--
 llvm/test/CodeGen/X86/abds.ll                 | 75 +++++++------------
 llvm/test/CodeGen/X86/abdu.ll                 | 60 +++++++--------
 4 files changed, 65 insertions(+), 93 deletions(-)

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index a867d88f76c0cf6..f33110c92355a23 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -10923,11 +10923,12 @@ SDValue DAGCombiner::foldABSToABD(SDNode *N) {
 
   // fold abs(sext(x) - sext(y)) -> zext(abds(x, y))
   // fold abs(zext(x) - zext(y)) -> zext(abdu(x, y))
-  // NOTE: Extensions must be equivalent.
-  if (VT1 == VT2 && hasOperation(ABDOpcode, VT1)) {
-    Op0 = Op0.getOperand(0);
-    Op1 = Op1.getOperand(0);
-    SDValue ABD = DAG.getNode(ABDOpcode, DL, VT1, Op0, Op1);
+  EVT MaxVT = VT1.bitsGT(VT2) ? VT1 : VT2;
+  if ((VT1 == MaxVT || Op0->hasOneUse()) &&
+      (VT2 == MaxVT || Op1->hasOneUse()) && hasOperation(ABDOpcode, MaxVT)) {
+    SDValue ABD = DAG.getNode(ABDOpcode, DL, MaxVT,
+                              DAG.getNode(ISD::TRUNCATE, DL, MaxVT, Op0),
+                              DAG.getNode(ISD::TRUNCATE, DL, MaxVT, Op1));
     ABD = DAG.getNode(ISD::ZERO_EXTEND, DL, VT, ABD);
     return DAG.getZExtOrTrunc(ABD, DL, SrcVT);
   }
diff --git a/llvm/test/CodeGen/AArch64/sve-abd.ll b/llvm/test/CodeGen/AArch64/sve-abd.ll
index 31a226ab74c9475..95aec0a49261997 100644
--- a/llvm/test/CodeGen/AArch64/sve-abd.ll
+++ b/llvm/test/CodeGen/AArch64/sve-abd.ll
@@ -248,17 +248,9 @@ define <vscale x 2 x i64> @uabd_d_promoted_ops(<vscale x 2 x i32> %a, <vscale x
 define <vscale x 4 x i32> @uabd_non_matching_extension(<vscale x 4 x i32> %a, <vscale x 4 x i8> %b) #0 {
 ; CHECK-LABEL: uabd_non_matching_extension:
 ; CHECK:       // %bb.0:
+; CHECK-NEXT:    ptrue p0.s
 ; CHECK-NEXT:    and z1.s, z1.s, #0xff
-; CHECK-NEXT:    uunpkhi z2.d, z0.s
-; CHECK-NEXT:    uunpklo z0.d, z0.s
-; CHECK-NEXT:    ptrue p0.d
-; CHECK-NEXT:    uunpkhi z3.d, z1.s
-; CHECK-NEXT:    uunpklo z1.d, z1.s
-; CHECK-NEXT:    sub z0.d, z0.d, z1.d
-; CHECK-NEXT:    sub z1.d, z2.d, z3.d
-; CHECK-NEXT:    abs z1.d, p0/m, z1.d
-; CHECK-NEXT:    abs z0.d, p0/m, z0.d
-; CHECK-NEXT:    uzp1 z0.s, z0.s, z1.s
+; CHECK-NEXT:    uabd z0.s, p0/m, z0.s, z1.s
 ; CHECK-NEXT:    ret
   %a.zext = zext <vscale x 4 x i32> %a to <vscale x 4 x i64>
   %b.zext = zext <vscale x 4 x i8> %b to <vscale x 4 x i64>
diff --git a/llvm/test/CodeGen/X86/abds.ll b/llvm/test/CodeGen/X86/abds.ll
index c5be2474c84d405..39ac47e99e6e989 100644
--- a/llvm/test/CodeGen/X86/abds.ll
+++ b/llvm/test/CodeGen/X86/abds.ll
@@ -50,16 +50,13 @@ define i8 @abd_ext_i8_i16(i8 %a, i16 %b) nounwind {
 ;
 ; X64-LABEL: abd_ext_i8_i16:
 ; X64:       # %bb.0:
-; X64-NEXT:    # kill: def $esi killed $esi def $rsi
-; X64-NEXT:    # kill: def $edi killed $edi def $rdi
-; X64-NEXT:    movsbq %dil, %rax
-; X64-NEXT:    movswq %si, %rcx
-; X64-NEXT:    movq %rax, %rdx
-; X64-NEXT:    subq %rcx, %rdx
-; X64-NEXT:    negq %rdx
-; X64-NEXT:    subq %rcx, %rax
-; X64-NEXT:    cmovleq %rdx, %rax
-; X64-NEXT:    # kill: def $al killed $al killed $rax
+; X64-NEXT:    movswl %si, %eax
+; X64-NEXT:    movsbl %dil, %ecx
+; X64-NEXT:    subl %eax, %ecx
+; X64-NEXT:    movl %ecx, %eax
+; X64-NEXT:    negl %eax
+; X64-NEXT:    cmovsl %ecx, %eax
+; X64-NEXT:    # kill: def $al killed $al killed $eax
 ; X64-NEXT:    retq
   %aext = sext i8 %a to i64
   %bext = sext i16 %b to i64
@@ -132,32 +129,25 @@ define i16 @abd_ext_i16(i16 %a, i16 %b) nounwind {
 define i16 @abd_ext_i16_i32(i16 %a, i32 %b) nounwind {
 ; X86-LABEL: abd_ext_i16_i32:
 ; X86:       # %bb.0:
-; X86-NEXT:    pushl %esi
 ; X86-NEXT:    movl {{[0-9]+}}(%esp), %ecx
-; X86-NEXT:    movl %ecx, %edx
-; X86-NEXT:    sarl $31, %edx
 ; X86-NEXT:    movswl {{[0-9]+}}(%esp), %eax
-; X86-NEXT:    movl %eax, %esi
-; X86-NEXT:    sarl $31, %esi
+; X86-NEXT:    movl %eax, %edx
+; X86-NEXT:    subl %ecx, %edx
+; X86-NEXT:    negl %edx
 ; X86-NEXT:    subl %ecx, %eax
-; X86-NEXT:    sbbl %edx, %esi
-; X86-NEXT:    sarl $31, %esi
-; X86-NEXT:    xorl %esi, %eax
-; X86-NEXT:    subl %esi, %eax
+; X86-NEXT:    cmovlel %edx, %eax
 ; X86-NEXT:    # kill: def $ax killed $ax killed $eax
-; X86-NEXT:    popl %esi
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: abd_ext_i16_i32:
 ; X64:       # %bb.0:
-; X64-NEXT:    # kill: def $edi killed $edi def $rdi
-; X64-NEXT:    movswq %di, %rax
-; X64-NEXT:    movslq %esi, %rcx
-; X64-NEXT:    movq %rax, %rdx
-; X64-NEXT:    subq %rcx, %rdx
-; X64-NEXT:    negq %rdx
-; X64-NEXT:    subq %rcx, %rax
-; X64-NEXT:    cmovleq %rdx, %rax
+; X64-NEXT:    movslq %esi, %rax
+; X64-NEXT:    movswl %di, %ecx
+; X64-NEXT:    movslq %ecx, %rcx
+; X64-NEXT:    subq %rax, %rcx
+; X64-NEXT:    movq %rcx, %rax
+; X64-NEXT:    negq %rax
+; X64-NEXT:    cmovsq %rcx, %rax
 ; X64-NEXT:    # kill: def $ax killed $ax killed $rax
 ; X64-NEXT:    retq
   %aext = sext i16 %a to i64
@@ -231,31 +221,24 @@ define i32 @abd_ext_i32(i32 %a, i32 %b) nounwind {
 define i32 @abd_ext_i32_i16(i32 %a, i16 %b) nounwind {
 ; X86-LABEL: abd_ext_i32_i16:
 ; X86:       # %bb.0:
-; X86-NEXT:    pushl %esi
 ; X86-NEXT:    movswl {{[0-9]+}}(%esp), %ecx
-; X86-NEXT:    movl %ecx, %edx
-; X86-NEXT:    sarl $31, %edx
 ; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
-; X86-NEXT:    movl %eax, %esi
-; X86-NEXT:    sarl $31, %esi
+; X86-NEXT:    movl %eax, %edx
+; X86-NEXT:    subl %ecx, %edx
+; X86-NEXT:    negl %edx
 ; X86-NEXT:    subl %ecx, %eax
-; X86-NEXT:    sbbl %edx, %esi
-; X86-NEXT:    sarl $31, %esi
-; X86-NEXT:    xorl %esi, %eax
-; X86-NEXT:    subl %esi, %eax
-; X86-NEXT:    popl %esi
+; X86-NEXT:    cmovlel %edx, %eax
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: abd_ext_i32_i16:
 ; X64:       # %bb.0:
-; X64-NEXT:    # kill: def $esi killed $esi def $rsi
-; X64-NEXT:    movslq %edi, %rax
-; X64-NEXT:    movswq %si, %rcx
-; X64-NEXT:    movq %rax, %rdx
-; X64-NEXT:    subq %rcx, %rdx
-; X64-NEXT:    negq %rdx
-; X64-NEXT:    subq %rcx, %rax
-; X64-NEXT:    cmovleq %rdx, %rax
+; X64-NEXT:    movslq %edi, %rcx
+; X64-NEXT:    movswl %si, %eax
+; X64-NEXT:    cltq
+; X64-NEXT:    subq %rax, %rcx
+; X64-NEXT:    movq %rcx, %rax
+; X64-NEXT:    negq %rax
+; X64-NEXT:    cmovsq %rcx, %rax
 ; X64-NEXT:    # kill: def $eax killed $eax killed $rax
 ; X64-NEXT:    retq
   %aext = sext i32 %a to i64
diff --git a/llvm/test/CodeGen/X86/abdu.ll b/llvm/test/CodeGen/X86/abdu.ll
index fe805528c435a52..11719be4ab5cd0c 100644
--- a/llvm/test/CodeGen/X86/abdu.ll
+++ b/llvm/test/CodeGen/X86/abdu.ll
@@ -50,14 +50,13 @@ define i8 @abd_ext_i8_i16(i8 %a, i16 %b) nounwind {
 ;
 ; X64-LABEL: abd_ext_i8_i16:
 ; X64:       # %bb.0:
-; X64-NEXT:    movzbl %dil, %eax
-; X64-NEXT:    movzwl %si, %ecx
-; X64-NEXT:    movq %rax, %rdx
-; X64-NEXT:    subq %rcx, %rdx
-; X64-NEXT:    negq %rdx
-; X64-NEXT:    subq %rcx, %rax
-; X64-NEXT:    cmovbeq %rdx, %rax
-; X64-NEXT:    # kill: def $al killed $al killed $rax
+; X64-NEXT:    movzwl %si, %eax
+; X64-NEXT:    movzbl %dil, %ecx
+; X64-NEXT:    subl %eax, %ecx
+; X64-NEXT:    movl %ecx, %eax
+; X64-NEXT:    negl %eax
+; X64-NEXT:    cmovsl %ecx, %eax
+; X64-NEXT:    # kill: def $al killed $al killed $eax
 ; X64-NEXT:    retq
   %aext = zext i8 %a to i64
   %bext = zext i16 %b to i64
@@ -130,25 +129,24 @@ define i16 @abd_ext_i16(i16 %a, i16 %b) nounwind {
 define i16 @abd_ext_i16_i32(i16 %a, i32 %b) nounwind {
 ; X86-LABEL: abd_ext_i16_i32:
 ; X86:       # %bb.0:
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %ecx
 ; X86-NEXT:    movzwl {{[0-9]+}}(%esp), %eax
-; X86-NEXT:    xorl %ecx, %ecx
-; X86-NEXT:    subl {{[0-9]+}}(%esp), %eax
-; X86-NEXT:    sbbl %ecx, %ecx
-; X86-NEXT:    sarl $31, %ecx
-; X86-NEXT:    xorl %ecx, %eax
+; X86-NEXT:    movl %eax, %edx
+; X86-NEXT:    subl %ecx, %edx
+; X86-NEXT:    negl %edx
 ; X86-NEXT:    subl %ecx, %eax
+; X86-NEXT:    cmovbel %edx, %eax
 ; X86-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: abd_ext_i16_i32:
 ; X64:       # %bb.0:
-; X64-NEXT:    movzwl %di, %eax
-; X64-NEXT:    movl %esi, %ecx
-; X64-NEXT:    movq %rax, %rdx
-; X64-NEXT:    subq %rcx, %rdx
-; X64-NEXT:    negq %rdx
-; X64-NEXT:    subq %rcx, %rax
-; X64-NEXT:    cmovbeq %rdx, %rax
+; X64-NEXT:    movl %esi, %eax
+; X64-NEXT:    movzwl %di, %ecx
+; X64-NEXT:    subq %rax, %rcx
+; X64-NEXT:    movq %rcx, %rax
+; X64-NEXT:    negq %rax
+; X64-NEXT:    cmovsq %rcx, %rax
 ; X64-NEXT:    # kill: def $ax killed $ax killed $rax
 ; X64-NEXT:    retq
   %aext = zext i16 %a to i64
@@ -224,23 +222,21 @@ define i32 @abd_ext_i32_i16(i32 %a, i16 %b) nounwind {
 ; X86:       # %bb.0:
 ; X86-NEXT:    movzwl {{[0-9]+}}(%esp), %ecx
 ; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
-; X86-NEXT:    xorl %edx, %edx
+; X86-NEXT:    movl %eax, %edx
+; X86-NEXT:    subl %ecx, %edx
+; X86-NEXT:    negl %edx
 ; X86-NEXT:    subl %ecx, %eax
-; X86-NEXT:    sbbl %edx, %edx
-; X86-NEXT:    sarl $31, %edx
-; X86-NEXT:    xorl %edx, %eax
-; X86-NEXT:    subl %edx, %eax
+; X86-NEXT:    cmovbel %edx, %eax
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: abd_ext_i32_i16:
 ; X64:       # %bb.0:
-; X64-NEXT:    movl %edi, %eax
-; X64-NEXT:    movzwl %si, %ecx
-; X64-NEXT:    movq %rax, %rdx
-; X64-NEXT:    subq %rcx, %rdx
-; X64-NEXT:    negq %rdx
-; X64-NEXT:    subq %rcx, %rax
-; X64-NEXT:    cmovbeq %rdx, %rax
+; X64-NEXT:    movl %edi, %ecx
+; X64-NEXT:    movzwl %si, %eax
+; X64-NEXT:    subq %rax, %rcx
+; X64-NEXT:    movq %rcx, %rax
+; X64-NEXT:    negq %rax
+; X64-NEXT:    cmovsq %rcx, %rax
 ; X64-NEXT:    # kill: def $eax killed $eax killed $rax
 ; X64-NEXT:    retq
   %aext = zext i32 %a to i64



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