Merge branch '19h1-fixes' into 19h1-fixes-on-master

tools/clang/test/CodeGenHLSL/quick-test/unused_matrix_input_regression.hlsl

@@ -0,0 +1,8 @@
+// RUN: %dxc /T vs_6_2 /E main %s | FileCheck %s
+
+// Regression test for GitHub #1947, where matrix input parameters were expected to have
+// exactly one use in HLSignatureLower, instead of zero or one, leading to a crash.
+
+// CHECK: ret void
+
+void main(int2x2 mat : IN) {}