[HLSL] Buffer handle globals should not be constants (#130231)

If these are constants their initializers will be removed by
InstCombine. Change them to not be constants and initialize them with
poison.

Author: bogner

clang/lib/CodeGen/CGHLSLRuntime.cpp

@@ -31,7 +31,6 @@
 #include "llvm/IR/Type.h"
 #include "llvm/IR/Value.h"
 #include "llvm/Support/Alignment.h"
-
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FormatVariadic.h"
 
@@ -245,12 +244,12 @@ void CGHLSLRuntime::addBuffer(const HLSLBufferDecl *BufDecl) {
   llvm::TargetExtType *TargetTy =
       cast<llvm::TargetExtType>(convertHLSLSpecificType(
           ResHandleTy, BufDecl->hasValidPackoffset() ? &Layout : nullptr));
-  llvm::GlobalVariable *BufGV =
-      new GlobalVariable(TargetTy, /*isConstant*/ true,
-                         GlobalValue::LinkageTypes::ExternalLinkage, nullptr,
-                         llvm::formatv("{0}{1}", BufDecl->getName(),
-                                       BufDecl->isCBuffer() ? ".cb" : ".tb"),
-                         GlobalValue::NotThreadLocal);
+  llvm::GlobalVariable *BufGV = new GlobalVariable(
+      TargetTy, /*isConstant*/ false,
+      GlobalValue::LinkageTypes::ExternalLinkage, PoisonValue::get(TargetTy),
+      llvm::formatv("{0}{1}", BufDecl->getName(),
+                    BufDecl->isCBuffer() ? ".cb" : ".tb"),
+      GlobalValue::NotThreadLocal);
   CGM.getModule().insertGlobalVariable(BufGV);
 
   // Add globals for constant buffer elements and create metadata nodes

clang/test/CodeGenHLSL/cbuffer.hlsl

@@ -4,8 +4,8 @@
 // CHECK: %__cblayout_CBScalars = type <{ float, double, half, i64, i32, i16, i32, i64 }>
 // CHECK: %__cblayout_CBVectors = type <{ <3 x float>, <3 x double>, <2 x half>, <3 x i64>, <4 x i32>, <3 x i16>, <3 x i64> }>
 // CHECK: %__cblayout_CBArrays = type <{ [3 x float], [2 x <3 x double>], [2 x [2 x half]], [3 x i64], [2 x [3 x [4 x <4 x i32>]]], [1 x i16], [2 x i64], [4 x i32] }>
-// CHECK: %__cblayout_CBStructs = type <{ target("dx.Layout", %A, 8, 0), target("dx.Layout", %B, 14, 0, 8), 
-// CHECK-SAME: target("dx.Layout", %C, 24, 0, 16), [5 x target("dx.Layout", %A, 8, 0)], 
+// CHECK: %__cblayout_CBStructs = type <{ target("dx.Layout", %A, 8, 0), target("dx.Layout", %B, 14, 0, 8),
+// CHECK-SAME: target("dx.Layout", %C, 24, 0, 16), [5 x target("dx.Layout", %A, 8, 0)],
 // CHECK-SAME: target("dx.Layout", %__cblayout_D, 94, 0), half, <3 x i16> }>
 
 // CHECK: %A = type <{ <2 x float> }>
@@ -39,7 +39,7 @@ cbuffer CBScalars : register(b1, space5) {
   int64_t a8;
 }
 
-// CHECK: @CBScalars.cb = external constant target("dx.CBuffer", target("dx.Layout", %__cblayout_CBScalars, 
+// CHECK: @CBScalars.cb = global target("dx.CBuffer", target("dx.Layout", %__cblayout_CBScalars,
 // CHECK-SAME: 56, 0, 8, 16, 24, 32, 36, 40, 48))
 // CHECK: @a1 = external addrspace(2) global float, align 4
 // CHECK: @a2 = external addrspace(2) global double, align 8
@@ -61,7 +61,7 @@ cbuffer CBVectors {
   // FIXME: add a bool vectors after llvm-project/llvm#91639 is added
 }
 
-// CHECK: @CBVectors.cb = external constant target("dx.CBuffer", target("dx.Layout", %__cblayout_CBVectors, 
+// CHECK: @CBVectors.cb = global target("dx.CBuffer", target("dx.Layout", %__cblayout_CBVectors,
 // CHECK-SAME: 136, 0, 16, 40, 48, 80, 96, 112))
 // CHECK: @b1 = external addrspace(2) global <3 x float>, align 16
 // CHECK: @b2 = external addrspace(2) global <3 x double>, align 32
@@ -82,7 +82,7 @@ cbuffer CBArrays : register(b2) {
   bool c8[4];
 }
 
-// CHECK: @CBArrays.cb = external constant target("dx.CBuffer", target("dx.Layout", %__cblayout_CBArrays, 
+// CHECK: @CBArrays.cb = global target("dx.CBuffer", target("dx.Layout", %__cblayout_CBArrays,
 // CHECK-SAME: 708, 0, 48, 112, 176, 224, 608, 624, 656))
 // CHECK: @c1 = external addrspace(2) global [3 x float], align 4
 // CHECK: @c2 = external addrspace(2) global [2 x <3 x double>], align 32
@@ -113,7 +113,7 @@ struct D {
   Empty es;
 };
 
-// CHECK: @CBStructs.cb = external constant target("dx.CBuffer", target("dx.Layout", %__cblayout_CBStructs, 
+// CHECK: @CBStructs.cb = global target("dx.CBuffer", target("dx.Layout", %__cblayout_CBStructs,
 // CHECK-SAME: 246, 0, 16, 32, 64, 144, 238, 240))
 // CHECK: @a = external addrspace(2) global target("dx.Layout", %A, 8, 0), align 8
 // CHECK: @b = external addrspace(2) global target("dx.Layout", %B, 14, 0, 8), align 8
@@ -137,7 +137,7 @@ struct Test {
     float a, b;
 };
 
-// CHECK: @CBMix.cb = external constant target("dx.CBuffer", target("dx.Layout", %__cblayout_CBMix,
+// CHECK: @CBMix.cb = global target("dx.CBuffer", target("dx.Layout", %__cblayout_CBMix,
 // CHECK-SAME: 170, 0, 24, 32, 120, 128, 136, 144, 152, 160, 168))
 // CHECK: @test = external addrspace(2) global [2 x target("dx.Layout", %Test, 8, 0, 4)], align 4
 // CHECK: @f1 = external addrspace(2) global float, align 4
@@ -161,9 +161,9 @@ cbuffer CBMix {
     float f7;
     vector<double,1> f8;
     uint16_t f9;
-};  
+};
 
-// CHECK: @CB_A.cb = external constant target("dx.CBuffer", target("dx.Layout", %__cblayout_CB_A, 188, 0, 32, 76, 80, 120, 128, 144, 160, 182))
+// CHECK: @CB_A.cb = global target("dx.CBuffer", target("dx.Layout", %__cblayout_CB_A, 188, 0, 32, 76, 80, 120, 128, 144, 160, 182))
 
 cbuffer CB_A {
   double B0[2];
@@ -177,7 +177,7 @@ cbuffer CB_A {
   half3 B8;
 }
 
-// CHECK: @CB_B.cb = external constant target("dx.CBuffer", target("dx.Layout", %__cblayout_CB_B, 94, 0, 88))
+// CHECK: @CB_B.cb = global target("dx.CBuffer", target("dx.Layout", %__cblayout_CB_B, 94, 0, 88))
 cbuffer CB_B {
   double3 B9[3];
   half3 B10;
@@ -212,7 +212,7 @@ struct G {
   half C3;
 };
 
-// CHECK: @CB_C.cb = external constant target("dx.CBuffer", target("dx.Layout", %__cblayout_CB_C, 400, 0, 16, 112, 128, 392))
+// CHECK: @CB_C.cb = global target("dx.CBuffer", target("dx.Layout", %__cblayout_CB_C, 400, 0, 16, 112, 128, 392))
 cbuffer CB_C {
   int D0;
   F D1;
@@ -254,10 +254,10 @@ void main() {
 // CHECK: ![[CBVECTORS]] = !{ptr @CBVectors.cb, ptr addrspace(2) @b1, ptr addrspace(2) @b2, ptr addrspace(2) @b3, ptr addrspace(2) @b4,
 // CHECK-SAME: ptr addrspace(2) @b5, ptr addrspace(2) @b6, ptr addrspace(2) @b7}
 
-// CHECK: ![[CBARRAYS]] = !{ptr @CBArrays.cb, ptr addrspace(2) @c1, ptr addrspace(2) @c2, ptr addrspace(2) @c3, ptr addrspace(2) @c4, 
+// CHECK: ![[CBARRAYS]] = !{ptr @CBArrays.cb, ptr addrspace(2) @c1, ptr addrspace(2) @c2, ptr addrspace(2) @c3, ptr addrspace(2) @c4,
 // CHECK-SAME: ptr addrspace(2) @c5, ptr addrspace(2) @c6, ptr addrspace(2) @c7, ptr addrspace(2) @c8}
 
-// CHECK: ![[CBSTRUCTS]] = !{ptr @CBStructs.cb, ptr addrspace(2) @a, ptr addrspace(2) @b, ptr addrspace(2) @c, ptr addrspace(2) @array_of_A, 
+// CHECK: ![[CBSTRUCTS]] = !{ptr @CBStructs.cb, ptr addrspace(2) @a, ptr addrspace(2) @b, ptr addrspace(2) @c, ptr addrspace(2) @array_of_A,
 // CHECK-SAME: ptr addrspace(2) @d, ptr addrspace(2) @e, ptr addrspace(2) @f}
 
 // CHECK: ![[CBMIX]] = !{ptr @CBMix.cb, ptr addrspace(2) @test, ptr addrspace(2) @f1, ptr addrspace(2) @f2, ptr addrspace(2) @f3,

clang/test/CodeGenHLSL/cbuffer_and_namespaces.hlsl

@@ -9,13 +9,13 @@
 // CHECK: %"n0::n2::__cblayout_C" = type <{ float, target("dx.Layout", %"n0::Foo", 4, 0) }>
 // CHECK: %"n0::Foo" = type <{ float }>
 
-// CHECK: @A.cb = external constant target("dx.CBuffer", target("dx.Layout", %"n0::n1::__cblayout_A", 4, 0))
+// CHECK: @A.cb = global target("dx.CBuffer", target("dx.Layout", %"n0::n1::__cblayout_A", 4, 0))
 // CHECK: @_ZN2n02n11aE = external addrspace(2) global float, align 4
 
-// CHECK: @B.cb = external constant target("dx.CBuffer", target("dx.Layout", %"n0::__cblayout_B", 4, 0))
+// CHECK: @B.cb = global target("dx.CBuffer", target("dx.Layout", %"n0::__cblayout_B", 4, 0))
 // CHECK: @_ZN2n01aE = external addrspace(2) global float, align 4
 
-// CHECK: @C.cb = external constant target("dx.CBuffer", target("dx.Layout", %"n0::n2::__cblayout_C", 20, 0, 16))
+// CHECK: @C.cb = global target("dx.CBuffer", target("dx.Layout", %"n0::n2::__cblayout_C", 20, 0, 16))
 // CHECK: @_ZN2n02n21aE = external addrspace(2) global float, align 4
 // CHECK: external addrspace(2) global target("dx.Layout", %"n0::Foo", 4, 0), align 4
 

clang/test/CodeGenHLSL/cbuffer_with_packoffset.hlsl

@@ -5,7 +5,7 @@
 // CHECK: %__cblayout_CB = type <{ float, double, <2 x i32> }>
 // CHECK: %__cblayout_CB_1 = type <{ float, <2 x float> }>
 
-// CHECK: @CB.cb = external constant target("dx.CBuffer", target("dx.Layout", %__cblayout_CB, 176, 16, 168, 88))
+// CHECK: @CB.cb = global target("dx.CBuffer", target("dx.Layout", %__cblayout_CB, 176, 16, 168, 88))
 // CHECK: @a = external addrspace(2) global float, align 4
 // CHECK: @b = external addrspace(2) global double, align 8
 // CHECK: @c = external addrspace(2) global <2 x i32>, align 8
@@ -16,7 +16,7 @@ cbuffer CB : register(b1, space3) {
   int2 c : packoffset(c5.z);
 }
 
-// CHECK: @CB.cb.1 = external constant target("dx.CBuffer", target("dx.Layout", %__cblayout_CB_1, 92, 88, 80))
+// CHECK: @CB.cb.1 = global target("dx.CBuffer", target("dx.Layout", %__cblayout_CB_1, 92, 88, 80))
 // CHECK: @x = external addrspace(2) global float, align 4
 // CHECK: @y = external addrspace(2) global <2 x float>, align 8
 

clang/test/CodeGenHLSL/cbuffer_with_static_global_and_function.hlsl

@@ -3,7 +3,7 @@
 
 // CHECK: %__cblayout_A = type <{ float }>
 
-// CHECK: @A.cb = external constant target("dx.CBuffer", target("dx.Layout", %__cblayout_A, 4, 0))
+// CHECK: @A.cb = global target("dx.CBuffer", target("dx.Layout", %__cblayout_A, 4, 0))
 // CHECK: @a = external addrspace(2) global float, align 4
 // CHECK-DAG: @_ZL1b = internal global float 3.000000e+00, align 4
 // CHECK-NOT: @B.cb

clang/test/CodeGenHLSL/default_cbuffer.hlsl

@@ -4,7 +4,7 @@
 // CHECK: %"__cblayout_$Globals" = type <{ float, float, target("dx.Layout", %__cblayout_S, 4, 0) }>
 // CHECK: %__cblayout_S = type <{ float }>
 
-// CHECK-DAG: @"$Globals.cb" = external constant target("dx.CBuffer", target("dx.Layout", %"__cblayout_$Globals", 20, 0, 4, 16))
+// CHECK-DAG: @"$Globals.cb" = global target("dx.CBuffer", target("dx.Layout", %"__cblayout_$Globals", 20, 0, 4, 16))
 // CHECK-DAG: @a = external addrspace(2) global float
 // CHECK-DAG: @g = external addrspace(2) global float
 // CHECK-DAG: @h = external addrspace(2) global target("dx.Layout", %__cblayout_S, 4, 0), align 4

clang/test/CodeGenHLSL/default_cbuffer_with_layout.hlsl

@@ -7,7 +7,7 @@
 
 // CHECK-DAG: @b = external addrspace(2) global float, align 4
 // CHECK-DAG: @d = external addrspace(2) global <4 x i32>, align 16
-// CHECK-DAG: @"$Globals.cb" = external constant target("dx.CBuffer",
+// CHECK-DAG: @"$Globals.cb" = global target("dx.CBuffer",
 // CHECK-DAG-SAME: target("dx.Layout", %"__cblayout_$Globals", 144, 120, 16, 32, 64, 128, 112))
 // CHECK-DAG: @a = external addrspace(2) global i32, align 4
 // CHECK-DAG: @c = external addrspace(2) global [4 x double], align 8

llvm/test/CodeGen/DirectX/Metadata/cbuffer_metadata.ll

@@ -6,13 +6,13 @@ target datalayout = "e-m:e-p:32:32-i1:32-i8:8-i16:16-i32:32-i64:64-f16:16-f32:32
 target triple = "dxil-pc-shadermodel6.6-compute"
 
 %__cblayout_CB1 = type <{ float, i32, double, <2 x i32> }>
-@CB1.cb = external constant target("dx.CBuffer", target("dx.Layout", %__cblayout_CB1, 24, 0, 4, 8, 16))
+@CB1.cb = global target("dx.CBuffer", target("dx.Layout", %__cblayout_CB1, 24, 0, 4, 8, 16)) poison
 
 %__cblayout_CB2 = type <{ float, double, float, half, i16, i64, i32 }>
-@CB2.cb = external constant target("dx.CBuffer", target("dx.Layout", %__cblayout_CB2, 36, 0, 8, 16, 20, 22, 24, 32))
+@CB2.cb = global target("dx.CBuffer", target("dx.Layout", %__cblayout_CB2, 36, 0, 8, 16, 20, 22, 24, 32)) poison
 
 %__cblayout_CB3 = type <{ double, <3 x float>, float, <3 x double>, half, <2 x double>, float, <3 x half>, <3 x half> }>
-@CB3.cb = external constant target("dx.CBuffer", target("dx.Layout", %__cblayout_CB3, 96, 0, 16, 28, 32, 56, 64, 80, 84, 90))
+@CB3.cb = global target("dx.CBuffer", target("dx.Layout", %__cblayout_CB3, 96, 0, 16, 28, 32, 56, 64, 80, 84, 90)) poison
 
 ; PRINT:; Resource Bindings:
 ; PRINT-NEXT:;