[llvm] 63b5b92 - [LazyValueInfo] Let getEdgeValueLocal look into freeze instructions

[Juneyoung Lee via llvm-commits]

Author: Juneyoung Lee
Date: 2020-08-11T16:39:34+09:00
New Revision: 63b5b92bc958291637bfd4ebb52e4f2eb58da1e6

URL: https://github.com/llvm/llvm-project/commit/63b5b92bc958291637bfd4ebb52e4f2eb58da1e6
DIFF: https://github.com/llvm/llvm-project/commit/63b5b92bc958291637bfd4ebb52e4f2eb58da1e6.diff

LOG: [LazyValueInfo] Let getEdgeValueLocal look into freeze instructions

This patch makes getEdgeValueLocal more precise when a freeze instruction is
given, by adding support for freeze into constantFoldUser

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D84629

Added: 
    

Modified: 
    llvm/lib/Analysis/LazyValueInfo.cpp
    llvm/test/Transforms/JumpThreading/freeze-lvi-edgevaluelocal.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/LazyValueInfo.cpp b/llvm/lib/Analysis/LazyValueInfo.cpp
index a95d1bca2fb5..bfc1c8f9be71 100644
--- a/llvm/lib/Analysis/LazyValueInfo.cpp
+++ b/llvm/lib/Analysis/LazyValueInfo.cpp
@@ -1221,11 +1221,11 @@ static bool usesOperand(User *Usr, Value *Op) {
 }
 
 // Return true if the instruction type of Val is supported by
-// constantFoldUser(). Currently CastInst and BinaryOperator only.  Call this
-// before calling constantFoldUser() to find out if it's even worth attempting
-// to call it.
+// constantFoldUser(). Currently CastInst, BinaryOperator and FreezeInst only.
+// Call this before calling constantFoldUser() to find out if it's even worth
+// attempting to call it.
 static bool isOperationFoldable(User *Usr) {
-  return isa<CastInst>(Usr) || isa<BinaryOperator>(Usr);
+  return isa<CastInst>(Usr) || isa<BinaryOperator>(Usr) || isa<FreezeInst>(Usr);
 }
 
 // Check if Usr can be simplified to an integer constant when the value of one
@@ -1256,6 +1256,9 @@ static ValueLatticeElement constantFoldUser(User *Usr, Value *Op,
             SimplifyBinOp(BO->getOpcode(), LHS, RHS, DL))) {
       return ValueLatticeElement::getRange(ConstantRange(C->getValue()));
     }
+  } else if (auto *FI = dyn_cast<FreezeInst>(Usr)) {
+    assert(FI->getOperand(0) == Op && "Operand 0 isn't Op");
+    return ValueLatticeElement::getRange(ConstantRange(OpConstVal));
   }
   return ValueLatticeElement::getOverdefined();
 }

diff  --git a/llvm/test/Transforms/JumpThreading/freeze-lvi-edgevaluelocal.ll b/llvm/test/Transforms/JumpThreading/freeze-lvi-edgevaluelocal.ll
index 07dd956777f6..db851c46ff5c 100644
--- a/llvm/test/Transforms/JumpThreading/freeze-lvi-edgevaluelocal.ll
+++ b/llvm/test/Transforms/JumpThreading/freeze-lvi-edgevaluelocal.ll
@@ -9,10 +9,7 @@ declare void @f3()
 define i32 @simple(i1 %cond) {
 ; CHECK-LABEL: @simple(
 ; CHECK-NEXT:  ENTRY:
-; CHECK-NEXT:    [[COND_FR:%.*]] = freeze i1 [[COND:%.*]]
-; CHECK-NEXT:    br i1 [[COND]], label [[A:%.*]], label [[EXIT:%.*]]
-; CHECK:       A:
-; CHECK-NEXT:    br i1 [[COND_FR]], label [[B:%.*]], label [[EXIT]]
+; CHECK-NEXT:    br i1 [[COND:%.*]], label [[B:%.*]], label [[EXIT:%.*]]
 ; CHECK:       B:
 ; CHECK-NEXT:    call void @f()
 ; CHECK-NEXT:    ret i32 1
@@ -36,8 +33,8 @@ define void @switch(i32 %cond) {
 ; CHECK-NEXT:  ENTRY:
 ; CHECK-NEXT:    [[COND_FR:%.*]] = freeze i32 [[COND:%.*]]
 ; CHECK-NEXT:    switch i32 [[COND]], label [[DEFAULT:%.*]] [
-; CHECK-NEXT:    i32 0, label [[A:%.*]]
-; CHECK-NEXT:    i32 1, label [[B:%.*]]
+; CHECK-NEXT:    i32 0, label [[A_TAKEN:%.*]]
+; CHECK-NEXT:    i32 1, label [[B_TAKEN:%.*]]
 ; CHECK-NEXT:    ]
 ; CHECK:       DEFAULT:
 ; CHECK-NEXT:    switch i32 [[COND_FR]], label [[PRESERVED1:%.*]] [
@@ -49,26 +46,12 @@ define void @switch(i32 %cond) {
 ; CHECK:       PRESERVED2:
 ; CHECK-NEXT:    call void @f2()
 ; CHECK-NEXT:    ret void
-; CHECK:       A:
-; CHECK-NEXT:    switch i32 [[COND_FR]], label [[A_NOTTAKEN:%.*]] [
-; CHECK-NEXT:    i32 0, label [[A_TAKEN:%.*]]
-; CHECK-NEXT:    ]
 ; CHECK:       A_TAKEN:
 ; CHECK-NEXT:    call void @f()
 ; CHECK-NEXT:    ret void
-; CHECK:       A_NOTTAKEN:
-; CHECK-NEXT:    call void @f2()
-; CHECK-NEXT:    ret void
-; CHECK:       B:
-; CHECK-NEXT:    switch i32 [[COND_FR]], label [[B_TAKEN:%.*]] [
-; CHECK-NEXT:    i32 0, label [[B_NOTTAKEN:%.*]]
-; CHECK-NEXT:    ]
 ; CHECK:       B_TAKEN:
 ; CHECK-NEXT:    call void @f()
 ; CHECK-NEXT:    ret void
-; CHECK:       B_NOTTAKEN:
-; CHECK-NEXT:    call void @f2()
-; CHECK-NEXT:    ret void
 ;
 ENTRY:
   %cond.fr = freeze i32 %cond