InstCombine: Simplify commonIDivTransforms

[oota-llvm.git] / lib / Analysis / InstructionSimplify.cpp

diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index 039d8286ecb803a01b904da17df48324a89772d7..a01bac2077f4f0b745a25823cb954e3740541b20 100644 (file)
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -1057,6 +1057,16 @@ static Value *SimplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
       (!isSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
     return Constant::getNullValue(Op0->getType());
 
+  // (X /u C1) /u C2 -> 0 if C1 * C2 overflow
+  ConstantInt *C1, *C2;
+  if (!isSigned && match(Op0, m_UDiv(m_Value(X), m_ConstantInt(C1))) &&
+      match(Op1, m_ConstantInt(C2))) {
+    bool Overflow;
+    C1->getValue().umul_ov(C2->getValue(), Overflow);
+    if (Overflow)
+      return Constant::getNullValue(Op0->getType());
+  }
+
   // If the operation is with the result of a select instruction, check whether
   // operating on either branch of the select always yields the same value.
   if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
@@ -1171,10 +1181,12 @@ static Value *SimplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
   if (Op0 == Op1)
     return Constant::getNullValue(Op0->getType());
 
-  // ((X % Y) % Y) -> (X % Y)
-  if (match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) {
+  // (X % Y) % Y -> X % Y
+  if ((Opcode == Instruction::SRem &&
+       match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
+      (Opcode == Instruction::URem &&
+       match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
     return Op0;
-  }
 
   // If the operation is with the result of a select instruction, check whether
   // operating on either branch of the select always yields the same value.