Fix scope fixing for address insts. (#2724)

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

2 files changed, 81 insertions, 0 deletions

diff --git a/tests/bugs/addr-scope-fix.slang b/tests/bugs/addr-scope-fix.slang
new file mode 100644
index 000000000..8a58b7daf
--- /dev/null
+++ b/tests/bugs/addr-scope-fix.slang
@@ -0,0 +1,76 @@
+//TEST(compute):COMPARE_COMPUTE_EX:-slang -compute -shaderobj -output-using-type
+
+//TEST_INPUT:ubuffer(data=[0 0 0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<float> outputBuffer;
+
+struct HitInfo
+{
+    float val;
+    float getVal() { return val; }
+}
+struct PathInfo
+{
+    HitInfo hit;
+    [mutating]
+    void setVal(float x)
+    {
+        hit.val = x;
+    }
+}
+
+void someOp(HitInfo hitInfo)
+{
+    outputBuffer[0] = hitInfo.val;
+}
+
+void func(int x)
+{
+    PathInfo path = {};
+    int i = 0;
+    if (x < 10)
+    {
+        // The `elementAddr(path, hit)` is first defined in this block.
+        // Note that this block dominates all remaining blocks in this
+        // function, so all future references to path.hit will use
+        // `elementAddr` inst defined here.
+        //
+        // The bug here is that when we emit code, the emit logic will
+        // find that the elementAddr inst is not in a valid region for
+        // future use and will try to create a local var for it. This will
+        // result a pointer typed var being created, and leads to invalid
+        // hlsl/glsl code.
+        // 
+        // The fix is to hoist all always-fold insts to earliest point
+        // in the program instead of creating a var for it.
+        //
+        someOp(path.hit);
+    }
+    else
+    {
+        // This return makes the true block dominate the rest of the blocks
+        // from a region that does not "dominate" the rest code regions.
+        return;
+    }
+
+    while (i < 3)
+    {
+        if (i < 2)
+        {
+            path.setVal(1);
+        }
+        else
+        {
+            path.setVal(2);
+        }
+
+        // This is the point where we are using path.hit again.
+        outputBuffer[i] = path.hit.getVal();
+        i++;
+    }
+}
+
+[numthreads(1, 1, 1)]
+void computeMain(uint3 dispatchThreadID: SV_DispatchThreadID)
+{
+    func(4);
+}
\ No newline at end of file
diff --git a/tests/bugs/addr-scope-fix.slang.expected.txt b/tests/bugs/addr-scope-fix.slang.expected.txt
new file mode 100644
index 000000000..73616c399
--- /dev/null
+++ b/tests/bugs/addr-scope-fix.slang.expected.txt
@@ -0,0 +1,5 @@
+type: float
+1.0
+1.0
+2.0
+