llvm-project

Author	SHA1	Message	Date
Craig Topper	074e845260	[X86] Prevent constant hoisting for a couple compare immediates that the selection DAG knows how to optimize into a shift. This allows "icmp ugt %a, 4294967295" and "icmp uge %a, 4294967296" to be optimized into right shifts by 32 which can fold the immediate into the shift instruction. These patterns show up with some regularity in real code. Unfortunately, since getImmCost can't see the icmp predicate we can't be tell if we're only catching these specific cases. llvm-svn: 256126	2015-12-20 18:41:54 +00:00

Author

SHA1

Message

Date

Craig Topper

074e845260

[X86] Prevent constant hoisting for a couple compare immediates that the selection DAG knows how to optimize into a shift.

This allows "icmp ugt %a, 4294967295" and "icmp uge %a, 4294967296" to be optimized into right shifts by 32 which can fold the immediate into the shift instruction. These patterns show up with some regularity in real code.

Unfortunately, since getImmCost can't see the icmp predicate we can't be tell if we're only catching these specific cases.

llvm-svn: 256126

2015-12-20 18:41:54 +00:00

1 Commits