[llvm-bugs] [Bug 47170] New: Sink instructions to their earliest usage site

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=47170

            Bug ID: 47170
           Summary: Sink instructions to their earliest usage site
           Product: new-bugs
           Version: unspecified
          Hardware: PC
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: new bugs
          Assignee: unassignedbugs at nondot.org
          Reporter: hiraditya at msn.com
                CC: htmldeveloper at gmail.com, llvm-bugs at lists.llvm.org

GVNSink can be improved to have this optimization.

https://reviews.llvm.org/D37762
Test case from the patch:

```

define i32 @test4(i1 %C, i1 %D, i1 %E, i32 %A) {
; CHECK-LABEL: @test4(
; CHECK-NEXT:    br i1 [[C:%.*]], label [[THEN:%.*]], label [[ENDIF:%.*]]
; CHECK:       then:
; CHECK-NEXT:    [[OR1:%.*]] = or i32 [[A:%.*]], 65537
; CHECK-NEXT:    [[SELECT1:%.*]] = select i1 [[D:%.*]], i32 [[OR1]], i32 [[A]]
; CHECK-NEXT:    [[OR2:%.*]] = or i32 [[SELECT1]], 131074
; CHECK-NEXT:    [[SELECT2:%.*]] = select i1 [[E:%.*]], i32 [[OR2]], i32
[[SELECT1]]
; CHECK-NEXT:    ret i32 [[SELECT2]]
; CHECK:       endif:
; CHECK-NEXT:    ret i32 [[A]]
;
  %or1 = or i32 %A, 65537
  %select1 = select i1 %D, i32 %or1, i32 %A
  %or2 = or i32 %select1, 131074
  %select2 = select i1 %E, i32 %or2, i32 %select1
  br i1 %C, label %then, label %endif

then:
  ret i32 %select2

endif:
  ret i32 %A
}
```

-- 
You are receiving this mail because:
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-bugs/attachments/20200814/b80ba6eb/attachment.html>