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[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
This commit is contained in:
Juneyoung Lee 2020-02-29 22:00:44 +09:00
parent af57b139a0
commit 9f1f244d3c
2 changed files with 47 additions and 4 deletions
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8
llvm/lib/Transforms/Scalar/LICM.cpp
View File

@ -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.

43
llvm/test/Transforms/LICM/freeze.ll Normal file
View File

@ -0,0 +1,43 @@
; 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)