Commit Graph

2 Commits

Author SHA1 Message Date
Hal Finkel
4029c3feed Disable PPC comparison optimization by default
This seems to cause a stage-2 LLVM compile failure (by crashing TableGen); do
I'm disabling this for now.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179807 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-18 22:54:25 +00:00
Hal Finkel
860c08cad5 Implement optimizeCompareInstr for PPC
Many PPC instructions have a so-called 'record form' which stores to a specific
condition register the result of comparing the result of the instruction with
zero (always as a signed comparison). For integer operations on PPC64, this is
always a 64-bit comparison.

This implementation is derived from the implementation in the ARM backend;
there are some differences because PPC condition registers are allocatable
virtual registers (although the record forms always use a specific one), and we
look for a matching subtraction instruction after the compare (but before the
first use) in addition to before it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179802 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-18 22:15:08 +00:00