[PATCH] D29587: [DAGCombiner] mulhi + 1 never overflow.

Eli Friedman via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Wed Mar 1 14:59:15 PST 2017


efriedma accepted this revision.
efriedma added a comment.
This revision is now accepted and ready to land.

LGTM.



================
Comment at: test/CodeGen/X86/overflow.ll:38
 ; X64:       # BB#0:
-; X64-NEXT:    movq %rdx, %rcx
-; X64-NEXT:    movq %rdi, %rax
-; X64-NEXT:    mulq %rsi
-; X64-NEXT:    andl $1, %ecx
-; X64-NEXT:    addq %rdx, %rcx
-; X64-NEXT:    setb %al
+; X64-NEXT:    xorl %eax, %eax
 ; X64-NEXT:    retq
----------------
Maybe change this test to return %7 rather than just one bit of the high half of %7, so the code isn't completely dead?  Not really important.


https://reviews.llvm.org/D29587





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