[llvm] 16e4e4a - [CodeGenPrep] Handle constants in ConvertPhiType

[David Green via llvm-commits]

Author: David Green
Date: 2022-10-13T16:41:44+01:00
New Revision: 16e4e4ab878aa148f0a4a56540c96a1725a960a2

URL: https://github.com/llvm/llvm-project/commit/16e4e4ab878aa148f0a4a56540c96a1725a960a2
DIFF: https://github.com/llvm/llvm-project/commit/16e4e4ab878aa148f0a4a56540c96a1725a960a2.diff

LOG: [CodeGenPrep] Handle constants in ConvertPhiType

This is a simple addition to the convertPhiTypes in CodeGenPrepare to
consider and convert constants as it converts the phi type. Someone
fixed the bug in the motivating example, so the undef is now a constant
0. This does mean converting between integer and floating point
constants, which may have different materialization.

Differential Revision: https://reviews.llvm.org/D135561

Added: 
    

Modified: 
    llvm/lib/CodeGen/CodeGenPrepare.cpp
    llvm/test/CodeGen/AArch64/convertphitype.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index f49d12748f3d..b9ffb8a8318f 100644
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -6122,6 +6122,7 @@ bool CodeGenPrepare::optimizePhiType(
   SmallVector<Instruction *, 4> Worklist;
   Worklist.push_back(cast<Instruction>(I));
   SmallPtrSet<PHINode *, 4> PhiNodes;
+  SmallPtrSet<ConstantData *, 4> Constants;
   PhiNodes.insert(I);
   Visited.insert(I);
   SmallPtrSet<Instruction *, 4> Defs;
@@ -6164,9 +6165,10 @@ bool CodeGenPrepare::optimizePhiType(
             AnyAnchored |= !isa<LoadInst>(OpBC->getOperand(0)) &&
                            !isa<ExtractElementInst>(OpBC->getOperand(0));
           }
-        } else if (!isa<UndefValue>(V)) {
+        } else if (auto *OpC = dyn_cast<ConstantData>(V))
+          Constants.insert(OpC);
+        else
           return false;
-        }
       }
     }
 
@@ -6208,7 +6210,8 @@ bool CodeGenPrepare::optimizePhiType(
   // Create all the new phi nodes of the new type, and bitcast any loads to the
   // correct type.
   ValueToValueMap ValMap;
-  ValMap[UndefValue::get(PhiTy)] = UndefValue::get(ConvertTy);
+  for (ConstantData *C : Constants)
+    ValMap[C] = ConstantExpr::getCast(Instruction::BitCast, C, ConvertTy);
   for (Instruction *D : Defs) {
     if (isa<BitCastInst>(D)) {
       ValMap[D] = D->getOperand(0);

diff  --git a/llvm/test/CodeGen/AArch64/convertphitype.ll b/llvm/test/CodeGen/AArch64/convertphitype.ll
index f6bfb69e510b..22d130d4000a 100644
--- a/llvm/test/CodeGen/AArch64/convertphitype.ll
+++ b/llvm/test/CodeGen/AArch64/convertphitype.ll
@@ -881,11 +881,11 @@ define float @convphi2_zero(i32 *%s, i32 *%d, i32 %n) {
 ; CHECK-NEXT:    br i1 [[CMP15]], label [[THEN:%.*]], label [[END:%.*]]
 ; CHECK:       then:
 ; CHECK-NEXT:    [[LS:%.*]] = load i32, i32* [[S:%.*]], align 4
+; CHECK-NEXT:    [[LS_BC:%.*]] = bitcast i32 [[LS]] to float
 ; CHECK-NEXT:    br label [[END]]
 ; CHECK:       end:
-; CHECK-NEXT:    [[PHI:%.*]] = phi i32 [ [[LS]], [[THEN]] ], [ 0, [[ENTRY:%.*]] ]
-; CHECK-NEXT:    [[B:%.*]] = bitcast i32 [[PHI]] to float
-; CHECK-NEXT:    ret float [[B]]
+; CHECK-NEXT:    [[PHI_TC:%.*]] = phi float [ [[LS_BC]], [[THEN]] ], [ 0.000000e+00, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    ret float [[PHI_TC]]
 ;
 entry:
   %cmp15 = icmp sgt i32 %n, 0
@@ -908,11 +908,11 @@ define i32 @convphi2f_zero(float *%s, float *%d, i32 %n) {
 ; CHECK-NEXT:    br i1 [[CMP15]], label [[THEN:%.*]], label [[END:%.*]]
 ; CHECK:       then:
 ; CHECK-NEXT:    [[LS:%.*]] = load float, float* [[S:%.*]], align 4
+; CHECK-NEXT:    [[LS_BC:%.*]] = bitcast float [[LS]] to i32
 ; CHECK-NEXT:    br label [[END]]
 ; CHECK:       end:
-; CHECK-NEXT:    [[PHI:%.*]] = phi float [ [[LS]], [[THEN]] ], [ 0.000000e+00, [[ENTRY:%.*]] ]
-; CHECK-NEXT:    [[B:%.*]] = bitcast float [[PHI]] to i32
-; CHECK-NEXT:    ret i32 [[B]]
+; CHECK-NEXT:    [[PHI_TC:%.*]] = phi i32 [ [[LS_BC]], [[THEN]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    ret i32 [[PHI_TC]]
 ;
 entry:
   %cmp15 = icmp sgt i32 %n, 0
@@ -935,11 +935,11 @@ define float @convphi2_ten(i32 *%s, i32 *%d, i32 %n) {
 ; CHECK-NEXT:    br i1 [[CMP15]], label [[THEN:%.*]], label [[END:%.*]]
 ; CHECK:       then:
 ; CHECK-NEXT:    [[LS:%.*]] = load i32, i32* [[S:%.*]], align 4
+; CHECK-NEXT:    [[LS_BC:%.*]] = bitcast i32 [[LS]] to float
 ; CHECK-NEXT:    br label [[END]]
 ; CHECK:       end:
-; CHECK-NEXT:    [[PHI:%.*]] = phi i32 [ [[LS]], [[THEN]] ], [ 10, [[ENTRY:%.*]] ]
-; CHECK-NEXT:    [[B:%.*]] = bitcast i32 [[PHI]] to float
-; CHECK-NEXT:    ret float [[B]]
+; CHECK-NEXT:    [[PHI_TC:%.*]] = phi float [ [[LS_BC]], [[THEN]] ], [ 0x36D4000000000000, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    ret float [[PHI_TC]]
 ;
 entry:
   %cmp15 = icmp sgt i32 %n, 0
@@ -962,11 +962,11 @@ define i32 @convphi2f_ten(float *%s, float *%d, i32 %n) {
 ; CHECK-NEXT:    br i1 [[CMP15]], label [[THEN:%.*]], label [[END:%.*]]
 ; CHECK:       then:
 ; CHECK-NEXT:    [[LS:%.*]] = load float, float* [[S:%.*]], align 4
+; CHECK-NEXT:    [[LS_BC:%.*]] = bitcast float [[LS]] to i32
 ; CHECK-NEXT:    br label [[END]]
 ; CHECK:       end:
-; CHECK-NEXT:    [[PHI:%.*]] = phi float [ [[LS]], [[THEN]] ], [ 1.000000e+01, [[ENTRY:%.*]] ]
-; CHECK-NEXT:    [[B:%.*]] = bitcast float [[PHI]] to i32
-; CHECK-NEXT:    ret i32 [[B]]
+; CHECK-NEXT:    [[PHI_TC:%.*]] = phi i32 [ [[LS_BC]], [[THEN]] ], [ 1092616192, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    ret i32 [[PHI_TC]]
 ;
 entry:
   %cmp15 = icmp sgt i32 %n, 0