[InstSimplify] (X << Y) % X -> 0
llvm-svn: 323182
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 6c6b1cf..245133f 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -1040,6 +1040,13 @@
match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
return Op0;
+ // (X << Y) % X -> 0
+ if ((Opcode == Instruction::SRem &&
+ match(Op0, m_NSWShl(m_Specific(Op1), m_Value()))) ||
+ (Opcode == Instruction::URem &&
+ match(Op0, m_NUWShl(m_Specific(Op1), m_Value()))))
+ 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))