Commit Graph

7 Commits

Author SHA1 Message Date
Evan Cheng 00b1a3cd7e Added a late machine instruction copy propagation pass. This catches
opportunities that only present themselves after late optimizations
such as tail duplication .e.g.
## BB#1:
        movl    %eax, %ecx
        movl    %ecx, %eax
        ret

The register allocator also leaves some of them around (due to false
dep between copies from phi-elimination, etc.)

This required some changes in codegen passes. Post-ra scheduler and the
pseudo-instruction expansion passes have been moved after branch folding
and tail merging. They were before branch folding before because it did
not always update block livein's. That's fixed now. The pass change makes
independently since we want to properly schedule instructions after
branch folding / tail duplication.

rdar://10428165
rdar://10640363

llvm-svn: 147716
2012-01-07 03:02:36 +00:00
Jim Grosbach 6d371ce37e Properly pseudo-ize the ARM LDMIA_RET instruction. This has the nice side-
effect that we get proper instruction printing using the "pop" mnemonic for it.

llvm-svn: 127502
2011-03-11 22:51:41 +00:00
Cameron Zwarich 5dd2aa2615 Eliminate the unused CodeGenPrepare option to split critical edges.
llvm-svn: 126825
2011-03-02 03:31:46 +00:00
Jakob Stoklund Olesen 4f3443e74d Explicitly disable CGP critical edge splitting for this test so it won't break
by reenabling it temporarily.

llvm-svn: 114858
2010-09-27 18:43:43 +00:00
Jakob Stoklund Olesen f2a279b902 Don't depend on basic block numbering.
llvm-svn: 114857
2010-09-27 18:43:40 +00:00
Evan Cheng dbcc4b4d4d Enable code placement optimization pass for ARM.
llvm-svn: 114746
2010-09-24 19:07:23 +00:00
Evan Cheng f259efde47 PHI elimination should not break back edge. It can cause some significant code placement issues. rdar://8263994
good:
LBB0_2:
  mov     r2, r0
  . . .
  mov     r1, r2
  bne     LBB0_2

bad:
LBB0_2:
  mov     r2, r0
  . . .
@ BB#3:
  mov     r1, r2
  b       LBB0_2

llvm-svn: 111221
2010-08-17 01:20:36 +00:00