[LVI] Take range metadata into account while calculating icmp condition constraints
Take range metadata into account for conditions like this:
%length = load i32, i32* %length_ptr, !range !{i32 0, i32 2147483647}
%cmp = icmp ult i32 %a, %length
This is a common pattern for range checks where the length of the array is dynamically loaded.
Reviewed By: sanjoy
Differential Revision: https://reviews.llvm.org/D23267
llvm-svn: 278496
diff --git a/llvm/lib/Analysis/LazyValueInfo.cpp b/llvm/lib/Analysis/LazyValueInfo.cpp
index c5c9027..8c09010 100644
--- a/llvm/lib/Analysis/LazyValueInfo.cpp
+++ b/llvm/lib/Analysis/LazyValueInfo.cpp
@@ -1211,6 +1211,9 @@
/*isFullSet=*/true);
if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS))
RHSRange = ConstantRange(CI->getValue());
+ else if (Instruction *I = dyn_cast<Instruction>(RHS))
+ if (auto *Ranges = I->getMetadata(LLVMContext::MD_range))
+ RHSRange = getConstantRangeFromMetadata(*Ranges);
// If we're interested in the false dest, invert the condition
CmpInst::Predicate Pred =