[PATCH] D36858: [x86] Teach the cmov converter to aggressively convert cmovs with memory operands into control flow.

[Amjad Aboud via Phabricator via llvm-commits]

aaboud added a comment.

Thanks Chandler for preparing the patch, the implementation looks elegant, however, it overlooked a case where the memory registers are a result of a previous CMOV instructions.
This is a small reproducer that result in bad MIR:

  target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
  target triple = "x86_64-unknown-unknown"
  
  define i32 @bar(i32* %a, i32* %b, i32 %n1, i32 %n2, i32 %d) #0 {
  entry:
    %cmp = icmp sgt i32 %n1, %n2
    %s = select i1 %cmp, i32* %a, i32* %b
    %p = getelementptr inbounds i32, i32* %s, i64 1
    %load = load i32, i32* %p, align 4
    %res = select i1 %cmp, i32 %d, i32 %load
    
    ret i32 %res
  }
  
  attributes #0 = {"target-cpu"="skylake"}


https://reviews.llvm.org/D36858