[PATCH] D153718: [SCCP] Don't always set MayIncludeUndef as true when calling markConstant

[luxufan via Phabricator via llvm-commits]

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In markConstant, MayIncludeUndef makes a difference when the Constant is
ConstantInt. Currently we hard code MayIncludeUndef as true, but in fact
only when there is at least one operand has
constantrange_including_undef, the simplifed result can
MayIncludingUndef.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D153718

Files:
  llvm/lib/Transforms/Utils/SCCPSolver.cpp
  llvm/test/Transforms/SCCP/ip-ranges-phis.ll


Index: llvm/test/Transforms/SCCP/ip-ranges-phis.ll
===================================================================
--- llvm/test/Transforms/SCCP/ip-ranges-phis.ll
+++ llvm/test/Transforms/SCCP/ip-ranges-phis.ll
@@ -56,11 +56,11 @@
 ; CHECK-NEXT:    [[V_2:%.*]] = select i1 [[C_2]], i32 20, i32 200
 ; CHECK-NEXT:    [[V_3:%.*]] = select i1 [[C_3]], i32 30, i32 300
 ; CHECK-NEXT:    [[R_1:%.*]] = add nuw nsw i32 [[V_1]], [[V_2]]
-; CHECK-NEXT:    [[R_2:%.*]] = add i32 [[R_1]], [[V_3]]
-; CHECK-NEXT:    [[R_3:%.*]] = add i32 [[R_2]], 400
-; CHECK-NEXT:    [[R_4:%.*]] = add i32 [[R_3]], 50
-; CHECK-NEXT:    [[R_5:%.*]] = add i32 [[R_4]], 60
-; CHECK-NEXT:    [[R_6:%.*]] = add i32 [[R_4]], 700
+; CHECK-NEXT:    [[R_2:%.*]] = add nuw nsw i32 [[R_1]], [[V_3]]
+; CHECK-NEXT:    [[R_3:%.*]] = add nuw nsw i32 [[R_2]], 400
+; CHECK-NEXT:    [[R_4:%.*]] = add nuw nsw i32 [[R_3]], 50
+; CHECK-NEXT:    [[R_5:%.*]] = add nuw nsw i32 [[R_4]], 60
+; CHECK-NEXT:    [[R_6:%.*]] = add nuw nsw i32 [[R_4]], 700
 ; CHECK-NEXT:    ret i32 [[R_6]]
 ;
 
@@ -111,7 +111,7 @@
 ; CHECK-NEXT:    [[P1:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ 1, [[IF_TRUE]] ]
 ; CHECK-NEXT:    [[P2:%.*]] = phi i32 [ 1, [[ENTRY]] ], [ -10, [[IF_TRUE]] ]
 ; CHECK-NEXT:    [[P3:%.*]] = phi i32 [ 1, [[ENTRY]] ], [ 10, [[IF_TRUE]] ]
-; CHECK-NEXT:    [[CALL1:%.*]] = tail call i32 @f2(i32 [[P1]], i32 [[P2]], i32 [[P3]], i1 [[CMP_1]], i1 [[CMP_2]])
+; CHECK-NEXT:    [[CALL1:%.*]] = tail call i32 @f2(i32 [[P1]], i32 [[P2]], i32 [[P3]], i1 [[CMP_1]], i1 [[CMP_2]]), !range [[RNG0:![0-9]+]]
 ; CHECK-NEXT:    ret i32 [[CALL1]]
 ;
 
@@ -204,7 +204,7 @@
 ; CHECK-NEXT:    br label [[END]]
 ; CHECK:       end:
 ; CHECK-NEXT:    [[P1:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ 5, [[IF_TRUE]] ]
-; CHECK-NEXT:    [[CALL1:%.*]] = tail call i32 @f3(i32 [[P1]], i32 [[Y]], i1 [[CMP_1]]), !range [[RNG0:![0-9]+]]
+; CHECK-NEXT:    [[CALL1:%.*]] = tail call i32 @f3(i32 [[P1]], i32 [[Y]], i1 [[CMP_1]]), !range [[RNG1:![0-9]+]]
 ; CHECK-NEXT:    ret i32 [[CALL1]]
 ;
 
Index: llvm/lib/Transforms/Utils/SCCPSolver.cpp
===================================================================
--- llvm/lib/Transforms/Utils/SCCPSolver.cpp
+++ llvm/lib/Transforms/Utils/SCCPSolver.cpp
@@ -1450,7 +1450,8 @@
       // after one of the operands go to overdefined, e.g. due to one operand
       // being a special floating value.
       ValueLatticeElement NewV;
-      NewV.markConstant(C, /*MayIncludeUndef=*/true);
+      NewV.markConstant(C, V1State.isConstantRangeIncludingUndef() ||
+                               V2State.isConstantRangeIncludingUndef());
       return (void)mergeInValue(&I, NewV);
     }
   }


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