Adjust bit cast instruction filter for DXIL Prepare pass (llvm#142678)

This PR addresses a specific edge case when deciding whether or not to
produce a bitcast instruction.
Specifically, when the given instruction is a global array, the element
type of the array wasn't correctly compared to the return type. In this
specific case, if the types are equal, a bitcast shouldn't be created,
but it was.
This PR checks to see if the element type of the array is the same as
the return type, and if it is, it doesn't create a bitcast instruction.

Fixes llvm#139013

Author: bob80905

llvm/lib/Target/DirectX/DXILPrepare.cpp

@@ -148,9 +148,49 @@ class DXILPrepareModule : public ModulePass {
                                      Type *Ty) {
     // Omit bitcasts if the incoming value matches the instruction type.
     auto It = PointerTypes.find(Operand);
-    if (It != PointerTypes.end())
-      if (cast<TypedPointerType>(It->second)->getElementType() == Ty)
+    if (It != PointerTypes.end()) {
+      auto *OpTy = cast<TypedPointerType>(It->second)->getElementType();
+      if (OpTy == Ty)
         return nullptr;
+    }
+
+    Type *ValTy = Operand->getType();
+    // Also omit the bitcast for matching global array types
+    if (auto *GlobalVar = dyn_cast<GlobalVariable>(Operand))
+      ValTy = GlobalVar->getValueType();
+
+    if (auto *AI = dyn_cast<AllocaInst>(Operand))
+      ValTy = AI->getAllocatedType();
+
+    if (auto *ArrTy = dyn_cast<ArrayType>(ValTy)) {
+      Type *ElTy = ArrTy->getElementType();
+      if (ElTy == Ty)
+        return nullptr;
+    }
+
+    // finally, drill down GEP instructions until we get the array
+    // that is being accessed, and compare element types
+    if (ConstantExpr *GEPInstr = dyn_cast<ConstantExpr>(Operand)) {
+      while (GEPInstr->getOpcode() == Instruction::GetElementPtr) {
+        Value *OpArg = GEPInstr->getOperand(0);
+        if (ConstantExpr *NewGEPInstr = dyn_cast<ConstantExpr>(OpArg)) {
+          GEPInstr = NewGEPInstr;
+          continue;
+        }
+
+        if (auto *GlobalVar = dyn_cast<GlobalVariable>(OpArg))
+          ValTy = GlobalVar->getValueType();
+        if (auto *AI = dyn_cast<AllocaInst>(Operand))
+          ValTy = AI->getAllocatedType();
+        if (auto *ArrTy = dyn_cast<ArrayType>(ValTy)) {
+          Type *ElTy = ArrTy->getElementType();
+          if (ElTy == Ty)
+            return nullptr;
+        }
+        break;
+      }
+    }
+
     // Insert bitcasts where we are removing the instruction.
     Builder.SetInsertPoint(&Inst);
     // This code only gets hit in opaque-pointer mode, so the type of the

llvm/test/CodeGen/DirectX/llc-vector-load-scalarize.ll

@@ -60,19 +60,15 @@ define <4 x i32> @load_array_vec_test() #0 {
 define <4 x i32> @load_vec_test() #0 {
 ; CHECK-LABEL: define <4 x i32> @load_vec_test(
 ; CHECK-SAME: ) #[[ATTR0]] {
-; CHECK-NEXT:    [[TMP1:%.*]] = bitcast ptr addrspace(3) @vecData.scalarized to ptr addrspace(3)
-; CHECK-NEXT:    [[TMP2:%.*]] = load i32, ptr addrspace(3) [[TMP1]], align 4
-; CHECK-NEXT:    [[TMP3:%.*]] = bitcast ptr addrspace(3) getelementptr (i32, ptr addrspace(3) @vecData.scalarized, i32 1) to ptr addrspace(3)
-; CHECK-NEXT:    [[TMP4:%.*]] = load i32, ptr addrspace(3) [[TMP3]], align 4
-; CHECK-NEXT:    [[TMP5:%.*]] = bitcast ptr addrspace(3) getelementptr (i32, ptr addrspace(3) @vecData.scalarized, i32 2) to ptr addrspace(3)
-; CHECK-NEXT:    [[TMP6:%.*]] = load i32, ptr addrspace(3) [[TMP5]], align 4
-; CHECK-NEXT:    [[TMP7:%.*]] = bitcast ptr addrspace(3) getelementptr (i32, ptr addrspace(3) @vecData.scalarized, i32 3) to ptr addrspace(3)
-; CHECK-NEXT:    [[TMP8:%.*]] = load i32, ptr addrspace(3) [[TMP7]], align 4
-; CHECK-NEXT:    [[DOTUPTO0:%.*]] = insertelement <4 x i32> poison, i32 [[TMP2]], i32 0
-; CHECK-NEXT:    [[DOTUPTO1:%.*]] = insertelement <4 x i32> [[DOTUPTO0]], i32 [[TMP4]], i32 1
-; CHECK-NEXT:    [[DOTUPTO2:%.*]] = insertelement <4 x i32> [[DOTUPTO1]], i32 [[TMP6]], i32 2
-; CHECK-NEXT:    [[TMP9:%.*]] = insertelement <4 x i32> [[DOTUPTO2]], i32 [[TMP8]], i32 3
-; CHECK-NEXT:    ret <4 x i32> [[TMP9]]
+; CHECK-NEXT:    [[TMP1:%.*]] = load i32, ptr addrspace(3) @vecData.scalarized, align 4
+; CHECK-NEXT:    [[TMP2:%.*]] = load i32, ptr addrspace(3) getelementptr (i32, ptr addrspace(3) @vecData.scalarized, i32 1), align 4
+; CHECK-NEXT:    [[TMP3:%.*]] = load i32, ptr addrspace(3) getelementptr (i32, ptr addrspace(3) @vecData.scalarized, i32 2), align 4
+; CHECK-NEXT:    [[TMP4:%.*]] = load i32, ptr addrspace(3) getelementptr (i32, ptr addrspace(3) @vecData.scalarized, i32 3), align 4
+; CHECK-NEXT:    [[DOTUPTO0:%.*]] = insertelement <4 x i32> poison, i32 [[TMP1]], i32 0
+; CHECK-NEXT:    [[DOTUPTO1:%.*]] = insertelement <4 x i32> [[DOTUPTO0]], i32 [[TMP2]], i32 1
+; CHECK-NEXT:    [[DOTUPTO2:%.*]] = insertelement <4 x i32> [[DOTUPTO1]], i32 [[TMP3]], i32 2
+; CHECK-NEXT:    [[TMP5:%.*]] = insertelement <4 x i32> [[DOTUPTO2]], i32 [[TMP4]], i32 3
+; CHECK-NEXT:    ret <4 x i32> [[TMP5]]
 ;
   %1 = load <4 x i32>, <4 x i32> addrspace(3)* @"vecData", align 4
   ret <4 x i32> %1
@@ -103,31 +99,23 @@ define <4 x i32> @load_static_array_of_vec_test(i32 %index) #0 {
 define <4 x i32> @multid_load_test() #0 {
 ; CHECK-LABEL: define <4 x i32> @multid_load_test(
 ; CHECK-SAME: ) #[[ATTR0]] {
-; CHECK-NEXT:    [[TMP1:%.*]] = bitcast ptr addrspace(3) @groushared2dArrayofVectors.scalarized.1dim to ptr addrspace(3)
-; CHECK-NEXT:    [[TMP2:%.*]] = load i32, ptr addrspace(3) [[TMP1]], align 4
-; CHECK-NEXT:    [[TMP3:%.*]] = bitcast ptr addrspace(3) getelementptr (i32, ptr addrspace(3) @groushared2dArrayofVectors.scalarized.1dim, i32 1) to ptr addrspace(3)
-; CHECK-NEXT:    [[TMP4:%.*]] = load i32, ptr addrspace(3) [[TMP3]], align 4
-; CHECK-NEXT:    [[TMP5:%.*]] = bitcast ptr addrspace(3) getelementptr (i32, ptr addrspace(3) @groushared2dArrayofVectors.scalarized.1dim, i32 2) to ptr addrspace(3)
-; CHECK-NEXT:    [[TMP6:%.*]] = load i32, ptr addrspace(3) [[TMP5]], align 4
-; CHECK-NEXT:    [[TMP7:%.*]] = bitcast ptr addrspace(3) getelementptr (i32, ptr addrspace(3) @groushared2dArrayofVectors.scalarized.1dim, i32 3) to ptr addrspace(3)
-; CHECK-NEXT:    [[TMP8:%.*]] = load i32, ptr addrspace(3) [[TMP7]], align 4
-; CHECK-NEXT:    [[TMP9:%.*]] = bitcast ptr addrspace(3) getelementptr inbounds ([36 x i32], ptr addrspace(3) @groushared2dArrayofVectors.scalarized.1dim, i32 0, i32 1) to ptr addrspace(3)
-; CHECK-NEXT:    [[TMP10:%.*]] = load i32, ptr addrspace(3) [[TMP9]], align 4
-; CHECK-NEXT:    [[TMP11:%.*]] = bitcast ptr addrspace(3) getelementptr (i32, ptr addrspace(3) getelementptr inbounds ([36 x i32], ptr addrspace(3) @groushared2dArrayofVectors.scalarized.1dim, i32 0, i32 1), i32 1) to ptr addrspace(3)
-; CHECK-NEXT:    [[TMP12:%.*]] = load i32, ptr addrspace(3) [[TMP11]], align 4
-; CHECK-NEXT:    [[TMP13:%.*]] = bitcast ptr addrspace(3) getelementptr (i32, ptr addrspace(3) getelementptr inbounds ([36 x i32], ptr addrspace(3) @groushared2dArrayofVectors.scalarized.1dim, i32 0, i32 1), i32 2) to ptr addrspace(3)
-; CHECK-NEXT:    [[TMP14:%.*]] = load i32, ptr addrspace(3) [[TMP13]], align 4
-; CHECK-NEXT:    [[TMP15:%.*]] = bitcast ptr addrspace(3) getelementptr (i32, ptr addrspace(3) getelementptr inbounds ([36 x i32], ptr addrspace(3) @groushared2dArrayofVectors.scalarized.1dim, i32 0, i32 1), i32 3) to ptr addrspace(3)
-; CHECK-NEXT:    [[TMP16:%.*]] = load i32, ptr addrspace(3) [[TMP15]], align 4
-; CHECK-NEXT:    [[DOTI05:%.*]] = add i32 [[TMP2]], [[TMP10]]
-; CHECK-NEXT:    [[DOTI16:%.*]] = add i32 [[TMP4]], [[TMP12]]
-; CHECK-NEXT:    [[DOTI27:%.*]] = add i32 [[TMP6]], [[TMP14]]
-; CHECK-NEXT:    [[DOTI38:%.*]] = add i32 [[TMP8]], [[TMP16]]
-; CHECK-NEXT:    [[DOTUPTO01215:%.*]] = insertelement <4 x i32> poison, i32 [[DOTI05]], i32 0
-; CHECK-NEXT:    [[DOTUPTO11316:%.*]] = insertelement <4 x i32> [[DOTUPTO01215]], i32 [[DOTI16]], i32 1
-; CHECK-NEXT:    [[DOTUPTO21417:%.*]] = insertelement <4 x i32> [[DOTUPTO11316]], i32 [[DOTI27]], i32 2
-; CHECK-NEXT:    [[TMP17:%.*]] = insertelement <4 x i32> [[DOTUPTO21417]], i32 [[DOTI38]], i32 3
-; CHECK-NEXT:    ret <4 x i32> [[TMP17]]
+; CHECK-NEXT:    [[TMP1:%.*]] = load i32, ptr addrspace(3) @groushared2dArrayofVectors.scalarized.1dim, align 4
+; CHECK-NEXT:    [[TMP2:%.*]] = load i32, ptr addrspace(3) getelementptr (i32, ptr addrspace(3) @groushared2dArrayofVectors.scalarized.1dim, i32 1), align 4
+; CHECK-NEXT:    [[TMP3:%.*]] = load i32, ptr addrspace(3) getelementptr (i32, ptr addrspace(3) @groushared2dArrayofVectors.scalarized.1dim, i32 2), align 4
+; CHECK-NEXT:    [[TMP4:%.*]] = load i32, ptr addrspace(3) getelementptr (i32, ptr addrspace(3) @groushared2dArrayofVectors.scalarized.1dim, i32 3), align 4
+; CHECK-NEXT:    [[TMP5:%.*]] = load i32, ptr addrspace(3) getelementptr inbounds ([36 x i32], ptr addrspace(3) @groushared2dArrayofVectors.scalarized.1dim, i32 0, i32 1), align 4
+; CHECK-NEXT:    [[DOTI13:%.*]] = load i32, ptr addrspace(3) getelementptr (i32, ptr addrspace(3) getelementptr inbounds ([36 x i32], ptr addrspace(3) @groushared2dArrayofVectors.scalarized.1dim, i32 0, i32 1), i32 1), align 4
+; CHECK-NEXT:    [[DOTI25:%.*]] = load i32, ptr addrspace(3) getelementptr (i32, ptr addrspace(3) getelementptr inbounds ([36 x i32], ptr addrspace(3) @groushared2dArrayofVectors.scalarized.1dim, i32 0, i32 1), i32 2), align 4
+; CHECK-NEXT:    [[DOTI37:%.*]] = load i32, ptr addrspace(3) getelementptr (i32, ptr addrspace(3) getelementptr inbounds ([36 x i32], ptr addrspace(3) @groushared2dArrayofVectors.scalarized.1dim, i32 0, i32 1), i32 3), align 4
+; CHECK-NEXT:    [[DOTI08:%.*]] = add i32 [[TMP1]], [[TMP5]]
+; CHECK-NEXT:    [[DOTI19:%.*]] = add i32 [[TMP2]], [[DOTI13]]
+; CHECK-NEXT:    [[DOTI210:%.*]] = add i32 [[TMP3]], [[DOTI25]]
+; CHECK-NEXT:    [[DOTI311:%.*]] = add i32 [[TMP4]], [[DOTI37]]
+; CHECK-NEXT:    [[DOTUPTO015:%.*]] = insertelement <4 x i32> poison, i32 [[DOTI08]], i32 0
+; CHECK-NEXT:    [[DOTUPTO116:%.*]] = insertelement <4 x i32> [[DOTUPTO015]], i32 [[DOTI19]], i32 1
+; CHECK-NEXT:    [[DOTUPTO217:%.*]] = insertelement <4 x i32> [[DOTUPTO116]], i32 [[DOTI210]], i32 2
+; CHECK-NEXT:    [[TMP6:%.*]] = insertelement <4 x i32> [[DOTUPTO217]], i32 [[DOTI311]], i32 3
+; CHECK-NEXT:    ret <4 x i32> [[TMP6]]
 ;
   %1 = load <4 x i32>, <4 x i32> addrspace(3)* getelementptr inbounds ([3 x [3 x <4 x i32>]], [3 x [3 x <4 x i32>]] addrspace(3)* @"groushared2dArrayofVectors", i32 0, i32 0, i32 0), align 4
   %2 = load <4 x i32>, <4 x i32> addrspace(3)* getelementptr inbounds ([3 x [3 x <4 x i32>]], [3 x [3 x <4 x i32>]] addrspace(3)* @"groushared2dArrayofVectors", i32 0, i32 1, i32 1), align 4

llvm/test/CodeGen/DirectX/noop_bitcast_global_array_type.ll

@@ -0,0 +1,53 @@
+; RUN: opt -S --dxil-prepare %s | FileCheck %s
+
+; Test that global arrays do not get a bitcast instruction
+; after the dxil-prepare pass.
+
+target triple = "dxilv1.2-unknown-shadermodel6.2-compute"
+
+@inputTile.1dim = local_unnamed_addr addrspace(3) global [3 x float] zeroinitializer, align 2
+
+; CHECK-LABEL: testload
+define float @testload() local_unnamed_addr {
+  ; NOTE: this would be "bitcast ptr addrspace(3)..." before the change that introduced this test,
+  ; after the dxil-prepare pass is run
+  ; CHECK-NEXT: load float, ptr addrspace(3) @inputTile.1dim, align 2
+  %v = load float, ptr addrspace(3) @inputTile.1dim, align 2  
+  
+  ret float %v
+}
+
+; CHECK-LABEL: teststore
+define void @teststore() local_unnamed_addr {  
+  ; CHECK-next: store float 2.000000e+00, ptr addrspace(3) @inputTile.1dim, align 2
+  store float 2.000000e+00, ptr addrspace(3) @inputTile.1dim, align 2  
+  
+  ret void
+}
+
+; CHECK-LABEL: testGEPConst
+define float @testGEPConst() local_unnamed_addr {  
+  ; CHECK-NEXT: load float, ptr addrspace(3) getelementptr (float, ptr addrspace(3) @inputTile.1dim, i32 1), align 4
+  %v = load float, ptr addrspace(3) getelementptr (float, ptr addrspace(3) @inputTile.1dim, i32 1), align 4
+  
+  ret float %v
+}
+
+; CHECK-LABEL: testGEPNonConst
+define float @testGEPNonConst(i32 %i) local_unnamed_addr {  
+  ; CHECK-NEXT: getelementptr float, ptr addrspace(3) @inputTile.1dim, i32 %i
+  %gep = getelementptr float, ptr addrspace(3) @inputTile.1dim, i32 %i
+  %v = load float, ptr addrspace(3) %gep
+  
+  ret float %v
+}
+
+; CHECK-LABEL: testAlloca
+define float @testAlloca(i32 %i) local_unnamed_addr {  
+  ; CHECK-NEXT: alloca [3 x float], align 4
+  %arr = alloca [3 x float], align 4
+  ; CHECK-NEXT: getelementptr [3 x float], ptr %arr, i32 1
+  %gep = getelementptr [3 x float], ptr %arr, i32 1
+  %v = load float, ptr %gep
+  ret float %v
+}