Working matrix swizzle (#1354)

* Working matrix swizzle.

Supports one and zero indexing and multiple elements.

Performs semantic checking of the swizzle.  Matrix swizzles are
transformed into a vector of indexing operations during lowering to the
IR.

This change does not handle matrix swizzle as lvalues.

* Renaming

* Added missing semicolon

* Initialize variable for gcc

* Added the expect file for diagnostics

* Matrix swizzle updated per PR feedback

* Stylistic fix

* Formatting fixes

* Fix compiling with AST change.
Change indentation.

Co-authored-by: jsmall-nvidia <jsmall@nvidia.com>

2 files changed, 38 insertions, 0 deletions

diff --git a/tests/language-feature/swizzles/matrix-swizzles.slang b/tests/language-feature/swizzles/matrix-swizzles.slang
new file mode 100644
index 000000000..e1a2d7473
--- /dev/null
+++ b/tests/language-feature/swizzles/matrix-swizzles.slang
@@ -0,0 +1,34 @@
+// matrix-swizzle.slang
+
+//TEST(compute):COMPARE_COMPUTE:
+
+// Test that matrix swizzle works correctly
+// Matrix swizzles can either be one or zero indexed
+// Reference: https://docs.microsoft.com/en-us/windows/win32/direct3dhlsl/dx-graphics-hlsl-per-component-math
+
+int test(int val)
+{
+    float2x2 worldMatrix = float2x2(val + 0, val + 1, val + 2, val + 3);
+    float2 tempVector1;
+    float2 tempVector2;
+
+    // TODO: make left-hand side matrix swizzles work
+    tempVector1 = worldMatrix._m00_m11;
+    tempVector2 = worldMatrix._12_21;
+
+    // return tempMatrix[0][0] + tempMatrix[0][1] = val + 0 + val + 1
+    return tempVector1.x + tempVector2.x;
+}
+
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<int> outputBuffer;
+
+[numthreads(4, 1, 1)]
+void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
+{
+    uint tid = dispatchThreadID.x;
+    int inVal = tid;
+    int outVal = test(inVal);
+    outputBuffer[tid] = outVal;
+}
diff --git a/tests/language-feature/swizzles/matrix-swizzles.slang.expected.txt b/tests/language-feature/swizzles/matrix-swizzles.slang.expected.txt
new file mode 100644
index 000000000..9b4237ab1
--- /dev/null
+++ b/tests/language-feature/swizzles/matrix-swizzles.slang.expected.txt
@@ -0,0 +1,4 @@
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