SPIRV Legalization fixes. (#3479)

* Fix CFG legalization for SPIRV backend.

* Emit DepthReplacing execution mode.

* Fix do-while lowering.

---------

Co-authored-by: Yong He <yhe@nvidia.com>

2 files changed, 61 insertions, 0 deletions

diff --git a/tests/spirv/depth-replacing.slang b/tests/spirv/depth-replacing.slang
new file mode 100644
index 000000000..df2ab17e1
--- /dev/null
+++ b/tests/spirv/depth-replacing.slang
@@ -0,0 +1,16 @@
+//TEST:SIMPLE(filecheck=CHECK): -target spirv -stage fragment -entry main -emit-spirv-directly
+
+struct PSOut
+{
+    float4 color : SV_Target;
+    float depth : SV_Depth;
+}
+// CHECK: OpExecutionMode {{.*}} DepthReplacing
+
+PSOut main()
+{
+    PSOut psout;
+    psout.color = float4(1.0f, 0.0f, 0.0f, 1.0f);
+    psout.depth = 0.5f;
+    return psout;
+}
diff --git a/tests/spirv/while-continue.slang b/tests/spirv/while-continue.slang
new file mode 100644
index 000000000..9c7b89295
--- /dev/null
+++ b/tests/spirv/while-continue.slang
@@ -0,0 +1,45 @@
+//TEST:SIMPLE(filecheck=CHECK): -target spirv -stage compute -entry main -emit-spirv-directly
+
+// Test that we can transform a continue in a while loop to valid spirv.
+
+uniform int loopCount;
+
+// CHECK: OpEntryPoint
+
+bool condition1()
+{
+    AllMemoryBarrier();
+    return output[2] < 1;
+}
+bool condition2()
+{
+    AllMemoryBarrier();
+    return output[3] < 1;
+}
+
+RWStructuredBuffer<float> output;
+
+[numthreads(1,1,1)]
+void main()
+{
+    float weight = 0.0;
+    do 
+    {
+        if (condition2()) 
+        { 
+            continue;
+        }
+        AllMemoryBarrier();
+    } while (condition1());
+
+    while(condition1())
+    {
+        if (condition2())
+        {
+            continue;
+        }
+        AllMemoryBarrier();
+    }
+
+    output[0] = weight;
+}