Commit 9f1f244d authored by Juneyoung Lee's avatar Juneyoung Lee
Browse files

[LICM] Allow freeze to hoist/sink out of a loop 

Summary: This patch allows LICM to hoist/sink freeze instructions out of a loop.

Reviewers: reames, fhahn, efriedma

Reviewed By: reames

Subscribers: jfb, lebedev.ri, hiraditya, asbirlea, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D75400
parent af57b139

llvm/lib/Transforms/Scalar/LICM.cpp

+4 −4
Original line number Diff line number Diff line
@@ -988,12 +988,12 @@ namespace { 
bool isHoistableAndSinkableInst(Instruction &I) {

  // Only these instructions are hoistable/sinkable.

  return (isa<LoadInst>(I) || isa<StoreInst>(I) || isa<CallInst>(I) ||

          isa<FenceInst>(I) || isa<CastInst>(I) ||

          isa<UnaryOperator>(I) || isa<BinaryOperator>(I) ||

          isa<SelectInst>(I) || isa<GetElementPtrInst>(I) || isa<CmpInst>(I) ||

          isa<FenceInst>(I) || isa<CastInst>(I) || isa<UnaryOperator>(I) ||

          isa<BinaryOperator>(I) || isa<SelectInst>(I) ||

          isa<GetElementPtrInst>(I) || isa<CmpInst>(I) ||

          isa<InsertElementInst>(I) || isa<ExtractElementInst>(I) ||

          isa<ShuffleVectorInst>(I) || isa<ExtractValueInst>(I) ||

          isa<InsertValueInst>(I));

          isa<InsertValueInst>(I) || isa<FreezeInst>(I));

}

/// Return true if all of the alias sets within this AST are known not to

/// contain a Mod, or if MSSA knows thare are no MemoryDefs in the loop.

llvm/test/Transforms/LICM/freeze.ll

0 → 100644
+43 −0
Original line number Diff line number Diff line 
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py

; RUN: opt -licm -S < %s | FileCheck %s



define void @hoist(i1 %a) {

; CHECK-LABEL: @hoist(

; CHECK-NEXT:  entry:

; CHECK-NEXT:    [[B:%.*]] = freeze i1 [[A:%.*]]

; CHECK-NEXT:    br label [[LOOP:%.*]]

; CHECK:       loop:

; CHECK-NEXT:    call void @use(i1 [[B]])

; CHECK-NEXT:    br label [[LOOP]]

;

entry:

  br label %loop

loop:

  %b = freeze i1 %a

  call void @use(i1 %b)

  br label %loop

}



define i1 @sink(i1 %a) {

; CHECK-LABEL: @sink(

; CHECK-NEXT:  entry:

; CHECK-NEXT:    br label [[LOOP:%.*]]

; CHECK:       loop:

; CHECK-NEXT:    [[C:%.*]] = call i1 @cond()

; CHECK-NEXT:    br i1 [[C]], label [[LOOP]], label [[EXIT:%.*]]

; CHECK:       exit:

; CHECK-NEXT:    [[FR_LE:%.*]] = freeze i1 [[A:%.*]]

; CHECK-NEXT:    ret i1 [[FR_LE]]

;

entry:

  br label %loop

loop:

  %fr = freeze i1 %a

  %c = call i1 @cond()

  br i1 %c, label %loop, label %exit

exit:

  ret i1 %fr

}



declare i1 @cond()

declare void @use(i1)