[PATCH] D60478: [InstCombine] Fix canonicalization of (-X s/ Y) to -(X s/ Y).

[Michael Liao via Phabricator via llvm-commits]

hliao created this revision.
hliao added a reviewer: shchenz.
Herald added subscribers: llvm-commits, hiraditya.
Herald added a project: LLVM.

- The previous patch seems quite messy.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D60478

Files:
  llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
  llvm/test/Transforms/InstCombine/div.ll


Index: llvm/test/Transforms/InstCombine/div.ll
===================================================================
--- llvm/test/Transforms/InstCombine/div.ll
+++ llvm/test/Transforms/InstCombine/div.ll
@@ -492,7 +492,7 @@
 define i8 @sdiv_negated_dividend_constant_divisor_smin(i8 %x) {
 ; CHECK-LABEL: @sdiv_negated_dividend_constant_divisor_smin(
 ; CHECK-NEXT:    [[TMP1:%.*]] = icmp eq i8 [[X:%.*]], -128
-; CHECK-NEXT:    [[D:%.*]] = zext i1 [[TMP1]] to i8
+; CHECK-NEXT:    [[D:%.*]] = sext i1 [[TMP1]] to i8
 ; CHECK-NEXT:    ret i8 [[D]]
 ;
   %neg = sub nsw i8 0, %x
@@ -503,7 +503,7 @@
 define <2 x i8> @sdiv_negated_dividend_constant_divisor_vec_splat_smin(<2 x i8> %x) {
 ; CHECK-LABEL: @sdiv_negated_dividend_constant_divisor_vec_splat_smin(
 ; CHECK-NEXT:    [[TMP1:%.*]] = icmp eq <2 x i8> [[X:%.*]], <i8 -128, i8 -128>
-; CHECK-NEXT:    [[D:%.*]] = zext <2 x i1> [[TMP1]] to <2 x i8>
+; CHECK-NEXT:    [[D:%.*]] = sext <2 x i1> [[TMP1]] to <2 x i8>
 ; CHECK-NEXT:    ret <2 x i8> [[D]]
 ;
   %neg = sub nsw <2 x i8> zeroinitializer, %x
@@ -522,9 +522,9 @@
 
 define <2 x i64> @sdiv_negated_dividend_constant_divisor_vec(<2 x i64> %x) {
 ; CHECK-LABEL: @sdiv_negated_dividend_constant_divisor_vec(
-; CHECK-NEXT:    [[NEG:%.*]] = sub nsw <2 x i64> zeroinitializer, [[X:%.*]]
-; CHECK-NEXT:    [[DIV:%.*]] = sdiv <2 x i64> [[NEG]], <i64 3, i64 4>
-; CHECK-NEXT:    ret <2 x i64> [[DIV]]
+; CHECK-NEXT:    [[DIV:%.*]] = sdiv <2 x i64> [[X:%.*]], <i64 3, i64 4>
+; CHECK-NEXT:    [[NEG:%.*]] = sub nsw <2 x i64> zeroinitializer, [[DIV]]
+; CHECK-NEXT:    ret <2 x i64> [[NEG]]
 ;
   %neg = sub nsw <2 x i64> zeroinitializer, %x
   %div = sdiv <2 x i64> %neg, <i64 3, i64 4>
@@ -533,9 +533,9 @@
 
 define <2 x i64> @sdiv_exact_negated_dividend_constant_divisor_vec(<2 x i64> %x) {
 ; CHECK-LABEL: @sdiv_exact_negated_dividend_constant_divisor_vec(
-; CHECK-NEXT:    [[NEG:%.*]] = sub nsw <2 x i64> zeroinitializer, [[X:%.*]]
-; CHECK-NEXT:    [[DIV:%.*]] = sdiv exact <2 x i64> [[NEG]], <i64 3, i64 4>
-; CHECK-NEXT:    ret <2 x i64> [[DIV]]
+; CHECK-NEXT:    [[DIV:%.*]] = sdiv exact <2 x i64> [[X:%.*]], <i64 3, i64 4>
+; CHECK-NEXT:    [[NEG:%.*]] = sub nsw <2 x i64> zeroinitializer, [[DIV]]
+; CHECK-NEXT:    ret <2 x i64> [[NEG]]
 ;
   %neg = sub nsw <2 x i64> zeroinitializer, %x
   %div = sdiv exact <2 x i64> %neg, <i64 3, i64 4>
@@ -546,9 +546,9 @@
 
 define <2 x i8> @sdiv_exact_negated_dividend_constant_divisor_vec_overflow(<2 x i8> %x) {
 ; CHECK-LABEL: @sdiv_exact_negated_dividend_constant_divisor_vec_overflow(
-; CHECK-NEXT:    [[NEG:%.*]] = sub nsw <2 x i8> zeroinitializer, [[X:%.*]]
-; CHECK-NEXT:    [[DIV:%.*]] = sdiv exact <2 x i8> [[NEG]], <i8 -128, i8 42>
-; CHECK-NEXT:    ret <2 x i8> [[DIV]]
+; CHECK-NEXT:    [[DIV:%.*]] = sdiv exact <2 x i8> [[X:%.*]], <i8 -128, i8 42>
+; CHECK-NEXT:    [[NEG:%.*]] = sub nsw <2 x i8> zeroinitializer, [[DIV]]
+; CHECK-NEXT:    ret <2 x i8> [[NEG]]
 ;
   %neg = sub nsw <2 x i8> zeroinitializer, %x
   %div = sdiv exact <2 x i8> %neg, <i8 -128, i8 42>
Index: llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -1015,6 +1015,12 @@
       (match(Op1, m_SExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1)))
     return BinaryOperator::CreateNeg(Op0);
 
+  // -X / Y --> -(X / Y)
+  Value *Y;
+  if (match(&I, m_SDiv(m_OneUse(m_NSWSub(m_Zero(), m_Value(X))), m_Value(Y))))
+    return BinaryOperator::CreateNSWNeg(
+        Builder.CreateSDiv(X, Y, I.getName(), I.isExact()));
+
   // X / INT_MIN --> X == INT_MIN
   if (match(Op1, m_SignMask()))
     return new ZExtInst(Builder.CreateICmpEQ(Op0, Op1), I.getType());
@@ -1043,12 +1049,6 @@
       Value *NarrowOp = Builder.CreateSDiv(Op0Src, NarrowDivisor);
       return new SExtInst(NarrowOp, Op0->getType());
     }
-  
-  // -X / Y --> -(X / Y)
-  Value *Y;
-  if (match(&I, m_SDiv(m_OneUse(m_NSWSub(m_Zero(), m_Value(X))), m_Value(Y))))
-    return BinaryOperator::CreateNSWNeg(
-        Builder.CreateSDiv(X, Y, I.getName(), I.isExact()));
 
     // -X / C --> X / -C (if the negation doesn't overflow).
     // TODO: This could be enhanced to handle arbitrary vector constants by


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