[llvm] [DirectX] Overlapping binding detection - check register space first (PR #152250)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-directx

Author: Helena Kotas (hekota)

<details>
<summary>Changes</summary>

The code that checks for overlapping binding did not compare register space when one of the bindings was for an unbounded resource array, leading to false errors. This change fixes it.

---
Full diff: https://github.com/llvm/llvm-project/pull/152250.diff


2 Files Affected:

- (modified) llvm/include/llvm/Analysis/DXILResource.h (+3-1) 
- (added) llvm/test/CodeGen/DirectX/Binding/binding-overlap-7.ll (+35) 


``````````diff
diff --git a/llvm/include/llvm/Analysis/DXILResource.h b/llvm/include/llvm/Analysis/DXILResource.h
index 93c6bfb057ef5..7b3e1a19753c8 100644
--- a/llvm/include/llvm/Analysis/DXILResource.h
+++ b/llvm/include/llvm/Analysis/DXILResource.h
@@ -360,9 +360,11 @@ class ResourceInfo {
              std::tie(RHS.RecordID, RHS.Space, RHS.LowerBound, RHS.Size);
     }
     bool overlapsWith(const ResourceBinding &RHS) const {
+      if (Space != RHS.Space)
+        return false;
       if (Size == UINT32_MAX)
         return LowerBound < RHS.LowerBound;
-      return Space == RHS.Space && LowerBound + Size - 1 >= RHS.LowerBound;
+      return LowerBound + Size - 1 >= RHS.LowerBound;
     }
   };
 
diff --git a/llvm/test/CodeGen/DirectX/Binding/binding-overlap-7.ll b/llvm/test/CodeGen/DirectX/Binding/binding-overlap-7.ll
new file mode 100644
index 0000000000000..25f81dd26b9db
--- /dev/null
+++ b/llvm/test/CodeGen/DirectX/Binding/binding-overlap-7.ll
@@ -0,0 +1,35 @@
+; Use llc for this test so that we don't abort after the first error.
+; RUN: not llc %s -o /dev/null 2>&1 | FileCheck %s
+
+; Check that there is no overlap with unbounded array in different space
+
+  ; Buffer<double> A[2] : register(t2, space4);
+  ; Buffer<double> B : register(t20, space5);  // does not overlap
+  ; Buffer<double> C[] : register(t2, space4); // overlaps with A
+
+; CHECK: error: resource A at register 2 overlaps with resource C at register 2 in space 4
+; CHECK-NOT: error: resource C at register 2 overlaps with resource B at register 20 in space 5
+
+target triple = "dxil-pc-shadermodel6.3-library"
+
+ at A.str = private unnamed_addr constant [2 x i8] c"A\00", align 1
+ at B.str = private unnamed_addr constant [2 x i8] c"B\00", align 1
+ at C.str = private unnamed_addr constant [2 x i8] c"C\00", align 1
+
+define void @test_not_overlapping_in_different_spaces() {
+entry:
+
+  ; Buffer<double> A[2] : register(t2, space4);
+  %h0 = call target("dx.TypedBuffer", double, 0, 0, 0)
+            @llvm.dx.resource.handlefrombinding(i32 4, i32 2, i32 2, i32 10, i1 false, ptr @A.str)
+
+  ; Buffer<double> B : register(t20, space5);
+  %h1 = call target("dx.TypedBuffer", i64, 0, 0, 0)
+            @llvm.dx.resource.handlefrombinding(i32 5, i32 20, i32 1, i32 0, i1 false, ptr @B.str)
+
+  ; Buffer<double> C[] : register(t2, space4);
+  %h2 = call target("dx.TypedBuffer", double, 0, 0, 0)
+            @llvm.dx.resource.handlefrombinding(i32 4, i32 2, i32 -1, i32 10, i1 false, ptr @C.str)
+
+  ret void
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/152250