2 files changed, 71 insertions, 3 deletions

diff --git a/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
index b4f4da6fb0..230b80e272 100644
--- a/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ b/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -336,6 +336,19 @@ Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) {
   return 0;
 }
 
+/// dyn_castZExtVal - Checks if V is a zext or constant that can
+/// be truncated to Ty without losing bits.
+static Value *dyn_castZExtVal(Value *V, const Type *Ty) {
+  if (ZExtInst *Z = dyn_cast<ZExtInst>(V)) {
+    if (Z->getSrcTy() == Ty)
+      return Z->getOperand(0);
+  } else if (ConstantInt *C = dyn_cast<ConstantInt>(V)) {
+    if (C->getValue().getActiveBits() <= cast<IntegerType>(Ty)->getBitWidth())
+      return ConstantExpr::getTrunc(C, Ty);
+  }
+  return 0;
+}
+
 Instruction *InstCombiner::visitUDiv(BinaryOperator &I) {
   Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
 
@@ -394,6 +407,14 @@ Instruction *InstCombiner::visitUDiv(BinaryOperator &I) {
       return SelectInst::Create(Cond, TSI, FSI);
     }
   }
+
+  // (zext A) udiv (zext B) --> zext (A udiv B)
+  if (ZExtInst *ZOp0 = dyn_cast<ZExtInst>(Op0))
+    if (Value *ZOp1 = dyn_castZExtVal(Op1, ZOp0->getSrcTy()))
+      return new ZExtInst(Builder->CreateUDiv(ZOp0->getOperand(0), ZOp1, "div",
+                                              I.isExact()),
+                          I.getType());
+
   return 0;
 }
 
@@ -568,7 +589,13 @@ Instruction *InstCombiner::visitURem(BinaryOperator &I) {
       return SelectInst::Create(Cond, TrueAnd, FalseAnd);
     }
   }
-  
+
+  // (zext A) urem (zext B) --> zext (A urem B)
+  if (ZExtInst *ZOp0 = dyn_cast<ZExtInst>(Op0))
+    if (Value *ZOp1 = dyn_castZExtVal(Op1, ZOp0->getSrcTy()))
+      return new ZExtInst(Builder->CreateURem(ZOp0->getOperand(0), ZOp1),
+                          I.getType());
+
   return 0;
 }
 
diff --git a/test/Transforms/InstCombine/udivrem-change-width.ll b/test/Transforms/InstCombine/udivrem-change-width.ll
index 9983944df8..b388a3b063 100644
--- a/test/Transforms/InstCombine/udivrem-change-width.ll
+++ b/test/Transforms/InstCombine/udivrem-change-width.ll
@@ -1,14 +1,16 @@
-; RUN: opt < %s -instcombine -S | not grep zext
-; PR4548
+; RUN: opt < %s -instcombine -S | FileCheck %s
 
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
 
+; PR4548
 define i8 @udiv_i8(i8 %a, i8 %b) nounwind {
   %conv = zext i8 %a to i32       
   %conv2 = zext i8 %b to i32      
   %div = udiv i32 %conv, %conv2   
   %conv3 = trunc i32 %div to i8   
   ret i8 %conv3
+; CHECK: @udiv_i8
+; CHECK: udiv i8 %a, %b
 }
 
 define i8 @urem_i8(i8 %a, i8 %b) nounwind {
@@ -17,5 +19,44 @@ define i8 @urem_i8(i8 %a, i8 %b) nounwind {
   %div = urem i32 %conv, %conv2   
   %conv3 = trunc i32 %div to i8   
   ret i8 %conv3
+; CHECK: @urem_i8
+; CHECK: urem i8 %a, %b
 }
 
+define i32 @udiv_i32(i8 %a, i8 %b) nounwind {
+  %conv = zext i8 %a to i32
+  %conv2 = zext i8 %b to i32
+  %div = udiv i32 %conv, %conv2
+  ret i32 %div
+; CHECK: @udiv_i32
+; CHECK: udiv i8 %a, %b
+; CHECK: zext
+}
+
+define i32 @urem_i32(i8 %a, i8 %b) nounwind {
+  %conv = zext i8 %a to i32
+  %conv2 = zext i8 %b to i32
+  %div = urem i32 %conv, %conv2
+  ret i32 %div
+; CHECK: @urem_i32
+; CHECK: urem i8 %a, %b
+; CHECK: zext
+}
+
+define i32 @udiv_i32_c(i8 %a) nounwind {
+  %conv = zext i8 %a to i32
+  %div = udiv i32 %conv, 10
+  ret i32 %div
+; CHECK: @udiv_i32_c
+; CHECK: udiv i8 %a, 10
+; CHECK: zext
+}
+
+define i32 @urem_i32_c(i8 %a) nounwind {
+  %conv = zext i8 %a to i32
+  %div = urem i32 %conv, 10
+  ret i32 %div
+; CHECK: @urem_i32_c
+; CHECK: urem i8 %a, 10
+; CHECK: zext
+}