[llvm] Reland "DAG: Preserve range metadata when load is narrowed" (#128144) (PR #130609)

[Matt Arsenault via llvm-commits]

================
@@ -0,0 +1,18 @@
+; RUN: llc -mtriple=x86_64-unknown-linux-gnu < %s
+;
+; This test case is reduced from RangeConstraintManager.cpp in a ASan build.
+; It crashes reduceLoadWidth in DAGCombiner.cpp. Preservation of range
+; metdata must ensure that ConstantRange truncation is strictly smaller.
+
+define i8 @_ZN12_GLOBAL__N_121SymbolicRangeInferrer19VisitBinaryOperatorILN5clang18BinaryOperatorKindE15EEENS2_4ento8RangeSetES5_S5_NS2_8QualTypeE(ptr %valptr) {
----------------
arsenm wrote:

Change function name to something nicer 

https://github.com/llvm/llvm-project/pull/130609