[llvm] 9f1f244 - [LICM] Allow freeze to hoist/sink out of a loop

[Juneyoung Lee via llvm-commits]

Author: Juneyoung Lee
Date: 2020-03-03T12:29:39+09:00
New Revision: 9f1f244d3cb8168021a56bcb661c2b08b7bd7cbd

URL: https://github.com/llvm/llvm-project/commit/9f1f244d3cb8168021a56bcb661c2b08b7bd7cbd
DIFF: https://github.com/llvm/llvm-project/commit/9f1f244d3cb8168021a56bcb661c2b08b7bd7cbd.diff

LOG: [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

Added: 
    llvm/test/Transforms/LICM/freeze.ll

Modified: 
    llvm/lib/Transforms/Scalar/LICM.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Scalar/LICM.cpp b/llvm/lib/Transforms/Scalar/LICM.cpp
index d429fc24dc33..ee436a4b3193 100644
--- a/llvm/lib/Transforms/Scalar/LICM.cpp
+++ b/llvm/lib/Transforms/Scalar/LICM.cpp
@@ -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.

diff  --git a/llvm/test/Transforms/LICM/freeze.ll b/llvm/test/Transforms/LICM/freeze.ll
new file mode 100644
index 000000000000..f17c270c97be
--- /dev/null
+++ b/llvm/test/Transforms/LICM/freeze.ll
@@ -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)