[llvm] [DirectX] Eliminate resource global variables from module (PR #114105)

[Justin Bogner via llvm-commits]

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@@ -0,0 +1,94 @@
+; RUN: opt -S -passes='early-cse<memssa>' %s -o %t
+; RUN: FileCheck --check-prefixes=CSE,CHECK %s < %t
+; finish compiling to verify that dxil-op-lower removes the globals entirely
+; RUN: opt -S -dxil-op-lower %t -o - | FileCheck --check-prefixes=LLC,CHECK %s
+; RUN: llc -mtriple=dxil-pc-shadermodel6.0-compute  --filetype=asm -o - %t | FileCheck --check-prefixes=LLC,CHECK %s
+; RUN: llc -mtriple=dxil-pc-shadermodel6.6-compute  --filetype=asm -o - %t | FileCheck --check-prefixes=LLC,CHECK %s
+
+; Ensure that EarlyCSE is able to eliminate unneeded loads of resource globals across typedBufferLoad.
+; Also that DXILOpLowering eliminates the globals entirely.
+
+target datalayout = "e-m:e-p:32:32-i1:32-i8:8-i16:16-i32:32-i64:64-f16:16-f32:32-f64:64-n8:16:32:64"
+target triple = "dxilv1.6-unknown-shadermodel6.6-compute"
+
+%"class.hlsl::RWBuffer" = type { target("dx.TypedBuffer", <4 x float>, 1, 0, 0) }
+
+; LLC-NOT: @In = global
+; LLC-NOT: @Out = global
+ at In = global %"class.hlsl::RWBuffer" zeroinitializer, align 4
+ at Out = global %"class.hlsl::RWBuffer" zeroinitializer, align 4
+
+; Function Attrs: convergent noinline norecurse
+; CHECK-LABEL define void @main()
+define void @main() local_unnamed_addr #0 {
+entry:
+  ; LLC: %In_h.i1 = call %dx.types.Handle @dx.op.createHandle
+  ; LLC: %Out_h.i2 = call %dx.types.Handle @dx.op.createHandle
+  %In_h.i = call target("dx.TypedBuffer", <4 x float>, 1, 0, 0) @llvm.dx.handle.fromBinding.tdx.TypedBuffer_v4f32_1_0_0t(i32 0, i32 0, i32 1, i32 0, i1 false)
+  store target("dx.TypedBuffer", <4 x float>, 1, 0, 0) %In_h.i, ptr @In, align 4
+  %Out_h.i = call target("dx.TypedBuffer", <4 x float>, 1, 0, 0) @llvm.dx.handle.fromBinding.tdx.TypedBuffer_v4f32_1_0_0t(i32 4, i32 1, i32 1, i32 0, i1 false)
+  store target("dx.TypedBuffer", <4 x float>, 1, 0, 0) %Out_h.i, ptr @Out, align 4
+  ; CSE: call i32 @llvm.dx.flattened.thread.id.in.group()
+  %0 = call i32 @llvm.dx.flattened.thread.id.in.group()
+  ; CHECK-NOT: load {{.*}} ptr @In
+  %1 = load target("dx.TypedBuffer", <4 x float>, 1, 0, 0), ptr @In, align 4
+  ; CSE: call noundef <4 x float> @llvm.dx.typedBufferLoad.v4f32.tdx.TypedBuffer_v4f32_1_0_0t
+  %2 = call noundef <4 x float> @llvm.dx.typedBufferLoad.v4f32.tdx.TypedBuffer_v4f32_1_0_0t(target("dx.TypedBuffer", <4 x float>, 1, 0, 0) %1, i32 %0)
+  ; CHECK-NOT: load {{.*}} ptr @In
+  %3 = load target("dx.TypedBuffer", <4 x float>, 1, 0, 0), ptr @In, align 4
+  %4 = call noundef <4 x float> @llvm.dx.typedBufferLoad.v4f32.tdx.TypedBuffer_v4f32_1_0_0t(target("dx.TypedBuffer", <4 x float>, 1, 0, 0) %3, i32 %0)
+  %add.i = fadd <4 x float> %2, %4
+  call void @llvm.dx.typedBufferStore.tdx.TypedBuffer_v4f32_1_0_0t.v4f32(target("dx.TypedBuffer", <4 x float>, 1, 0, 0) %Out_h.i, i32 %0, <4 x float> %add.i)
+  ; CHECK: ret void
+  ret void
+}
+
+; Function Attrs: mustprogress nofree nosync nounwind willreturn memory(none)
+declare i32 @llvm.dx.flattened.thread.id.in.group() #1
+
+; Function Attrs: mustprogress nocallback nofree nosync nounwind willreturn
+; CSE: declare <4 x float> @llvm.dx.typedBufferLoad.v4f32.tdx.TypedBuffer_v4f32_1_0_0t(target("dx.TypedBuffer", <4 x float>, 1, 0, 0), i32) [[ROAttr:#[0-9]+]]
+declare <4 x float> @llvm.dx.typedBufferLoad.v4f32.tdx.TypedBuffer_v4f32_1_0_0t(target("dx.TypedBuffer", <4 x float>, 1, 0, 0), i32) #2
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bogner wrote:

We're declaring the intrinsic with the wrong attributes here and then testing that it gets overwritten with the correct ones? That's kind of a weird thing to do...

I'd probably leave the declarations of the intrinsics out entirely since they'll be declared implicitly anyway.

https://github.com/llvm/llvm-project/pull/114105