[ValueTracking][ConstantRange] Distinguish low/high always overflow
In order to fold an always overflowing signed saturating add/sub,
we need to know in which direction the always overflow occurs.
This patch splits up AlwaysOverflows into AlwaysOverflowsLow and
AlwaysOverflowsHigh to pass through this information (but it is
not used yet).
Differential Revision: https://reviews.llvm.org/D62463
llvm-svn: 361858
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index d46ddc4..6400637 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -3992,8 +3992,10 @@
switch (OR) {
case ConstantRange::OverflowResult::MayOverflow:
return OverflowResult::MayOverflow;
- case ConstantRange::OverflowResult::AlwaysOverflows:
- return OverflowResult::AlwaysOverflows;
+ case ConstantRange::OverflowResult::AlwaysOverflowsLow:
+ return OverflowResult::AlwaysOverflowsLow;
+ case ConstantRange::OverflowResult::AlwaysOverflowsHigh:
+ return OverflowResult::AlwaysOverflowsHigh;
case ConstantRange::OverflowResult::NeverOverflows:
return OverflowResult::NeverOverflows;
}