Correctly pass values from the conditional block to the loop during inversion (#3311)

Co-authored-by: Yong He <yonghe@outlook.com>

1 files changed, 32 insertions, 0 deletions

diff --git a/tests/bugs/inversion-tricky-phi.slang b/tests/bugs/inversion-tricky-phi.slang
new file mode 100644
index 000000000..c0a6417f2
--- /dev/null
+++ b/tests/bugs/inversion-tricky-phi.slang
@@ -0,0 +1,32 @@
+//TEST:SIMPLE(filecheck=CHECK): -stage compute -entry computeMain -target hlsl
+
+// Annoyingly, the reproducer for this doesn't terminate, so just check that we
+// succeeded compilation.
+// Previously, this would fail in SCCP after loop inversion failed to account
+// for condition variables being used in the loop.
+// CHECK: computeMain
+
+//TEST_INPUT:ubuffer(data=[0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<float> outputBuffer;
+
+[numthreads(1, 1, 1)]
+void computeMain(uint i : SV_GroupIndex)
+{
+    float x = 0;
+    f(x);
+    outputBuffer[i] = x;
+}
+
+void f(inout float r)
+{
+    r = 0;
+    float a = 0;
+    do {
+        do {
+            a = a + 1;
+            if (a > 0)
+                break;
+        } while (true);
+        r = a;
+    } while (true);
+}