This small refinement to the -fsplit-stack prologue arg pointer
initialization improves code generation. Compare the -O2
gcc/testsuite/gcc.dg/split-3.c code for down() below.
before after
mflr 0 mflr 0
std 31,-8(1) std 31,-8(1)
std 0,16(1) mr 12,1
stdu 1,-10144(1) std 0,16(1)
addi 12,1,10144 stdu 1,-10144(1)
bge 7,.L7 bge 7,.L7
mr 12,29 mr 12,29
.L7: .L7:
* config/rs6000/rs6000.c (rs6000_emit_allocate_stack): Return
stack adjusting insn. Formatting.
(rs6000_emit_prologue): Track stack adjusting insn, and use of
r12. If possible, emit first -fsplit-stack arg pointer insn
before stack adjust. Don't use r12 to save cr if split-stack.
This patch is okay. Nice improvement.
Thanks, David
