Changes in directory llvm/lib/Target/X86:
README.txt updated: 1.90 -> 1.91 --- Log message: Another entry --- Diffs of the changes: (+35 -0) README.txt | 35 +++++++++++++++++++++++++++++++++++ 1 files changed, 35 insertions(+) Index: llvm/lib/Target/X86/README.txt diff -u llvm/lib/Target/X86/README.txt:1.90 llvm/lib/Target/X86/README.txt:1.91 --- llvm/lib/Target/X86/README.txt:1.90 Mon Apr 17 19:21:01 2006 +++ llvm/lib/Target/X86/README.txt Mon Apr 17 20:22:57 2006 @@ -961,3 +961,38 @@ to three-address transformation. It also exposes some other problems. See MOV32ri -3 and the spills. + +//===---------------------------------------------------------------------===// + +http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25500 + +LLVM is producing bad code. + +LBB_main_4: # cond_true44 + addps %xmm1, %xmm2 + subps %xmm3, %xmm2 + movaps (%ecx), %xmm4 + movaps %xmm2, %xmm1 + addps %xmm4, %xmm1 + addl $16, %ecx + incl %edx + cmpl $262144, %edx + movaps %xmm3, %xmm2 + movaps %xmm4, %xmm3 + jne LBB_main_4 # cond_true44 + +There are two problems. 1) No need to two loop induction variables. We can +compare against 262144 * 16. 2) Poor register allocation decisions. We should +be able eliminate one of the movaps: + + addps %xmm1, %xmm2 + subps %xmm3, %xmm2 + movaps (%ecx), %xmm4 + movaps %xmm2, %xmm2 <=== Eliminate! + addps %xmm4, %xmm2 + addl $16, %ecx + incl %edx + cmpl $262144, %edx + movaps %xmm3, %xmm1 + movaps %xmm4, %xmm3 + jne LBB_main_4 # cond_true44 _______________________________________________ llvm-commits mailing list llvm-commits@cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
