For functions where esi is used as base pointer, we would previously fall back
from lowering memcpy with "rep movs" because that clobbers esi.
With this patch, we just store esi in another physical register, and restore
it afterwards. This adds a little bit of register preassure, but the more
efficient memcpy should be worth it.
Differential Revision: http://llvm-reviews.chandlerc.com/D2968
llvm-svn: 204174
selection dag (PR19012)
In X86SelectionDagInfo::EmitTargetCodeForMemcpy we check with MachineFrameInfo
to make sure that ESI isn't used as a base pointer register before we choose to
emit rep movs (which clobbers esi).
The problem is that MachineFrameInfo wouldn't know about dynamic allocas or
inline asm that clobbers the stack pointer until SelectionDAGBuilder has
encountered them.
This patch fixes the problem by checking for such things when building the
FunctionLoweringInfo.
Differential Revision: http://llvm-reviews.chandlerc.com/D2954
llvm-svn: 202930
This was done with the following sed invocation to catch label lines demarking function boundaries:
sed -i '' "s/^;\( *\)\([A-Z0-9_]*\):\( *\)test\([A-Za-z0-9_-]*\):\( *\)$/;\1\2-LABEL:\3test\4:\5/g" test/CodeGen/*/*.ll
which was written conservatively to avoid false positives rather than false negatives. I scanned through all the changes and everything looks correct.
llvm-svn: 186258
This happens when there is both stack realignment and a dynamic alloca in the
function. If we overwrite %esi (rep;movsl uses fixed registers) we'll lose the
base pointer and the next register spill will write into oblivion.
Fixes PR15249 and unbreaks firefox on i386/freebsd. Mozilla uses dynamic allocas
and freebsd a 4 byte stack alignment.
llvm-svn: 175057
