[PATCH] D105789: [SelectionDAG] Check use before combining into USUBSAT

[Qiu Chaofan via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG954a15d6398e: [SelectionDAG] Check use before combining into USUBSAT (authored by qiucf).

Changed prior to commit:
  https://reviews.llvm.org/D105789?vs=357838&id=358177#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D105789/new/

https://reviews.llvm.org/D105789

Files:
  llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
  llvm/test/CodeGen/PowerPC/sat-add.ll


Index: llvm/test/CodeGen/PowerPC/sat-add.ll
===================================================================
--- llvm/test/CodeGen/PowerPC/sat-add.ll
+++ llvm/test/CodeGen/PowerPC/sat-add.ll
@@ -864,3 +864,33 @@
   ret <4 x i128> %c
 }
 
+define i64 @unsigned_sat_constant_i64_with_single_use(i64 %x) {
+; CHECK-LABEL: unsigned_sat_constant_i64_with_single_use:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    addi 4, 3, -4
+; CHECK-NEXT:    cmpld 4, 3
+; CHECK-NEXT:    iselgt 3, 0, 4
+; CHECK-NEXT:    blr
+  %umin = call i64 @llvm.umin.i64(i64 %x, i64 4)
+  %sub = sub i64 %x, %umin
+  ret i64 %sub
+}
+
+define i64 @unsigned_sat_constant_i64_with_multiple_use(i64 %x, i64 %y) {
+; CHECK-LABEL: unsigned_sat_constant_i64_with_multiple_use:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    li 5, 4
+; CHECK-NEXT:    cmpldi 3, 4
+; CHECK-NEXT:    isellt 5, 3, 5
+; CHECK-NEXT:    sub 3, 3, 5
+; CHECK-NEXT:    add 4, 4, 5
+; CHECK-NEXT:    mulld 3, 3, 4
+; CHECK-NEXT:    blr
+  %umin = call i64 @llvm.umin.i64(i64 %x, i64 4)
+  %sub = sub i64 %x, %umin
+  %add = add i64 %y, %umin
+  %res = mul i64 %sub, %add
+  ret i64 %res
+}
+
+declare i64 @llvm.umin.i64(i64, i64)
Index: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -3209,7 +3209,7 @@
 
   // Try to find umax(a,b) - b or a - umin(a,b) patterns
   // they may be converted to usubsat(a,b).
-  if (Op0.getOpcode() == ISD::UMAX) {
+  if (Op0.getOpcode() == ISD::UMAX && Op0.hasOneUse()) {
     SDValue MaxLHS = Op0.getOperand(0);
     SDValue MaxRHS = Op0.getOperand(1);
     if (MaxLHS == Op1)
@@ -3218,7 +3218,7 @@
       return getTruncatedUSUBSAT(DstVT, SubVT, MaxLHS, Op1, DAG, SDLoc(N));
   }
 
-  if (Op1.getOpcode() == ISD::UMIN) {
+  if (Op1.getOpcode() == ISD::UMIN && Op1.hasOneUse()) {
     SDValue MinLHS = Op1.getOperand(0);
     SDValue MinRHS = Op1.getOperand(1);
     if (MinLHS == Op0)
@@ -3229,7 +3229,8 @@
 
   // sub(a,trunc(umin(zext(a),b))) -> usubsat(a,trunc(umin(b,SatLimit)))
   if (Op1.getOpcode() == ISD::TRUNCATE &&
-      Op1.getOperand(0).getOpcode() == ISD::UMIN) {
+      Op1.getOperand(0).getOpcode() == ISD::UMIN &&
+      Op1.getOperand(0).hasOneUse()) {
     SDValue MinLHS = Op1.getOperand(0).getOperand(0);
     SDValue MinRHS = Op1.getOperand(0).getOperand(1);
     if (MinLHS.getOpcode() == ISD::ZERO_EXTEND && MinLHS.getOperand(0) == Op0)


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