Add support for explicit register space bindings (#542)

This change adds support for specifying explicit register spaces, like:

```hlsl
// Bind to texture register #2 in space #1
Texture2D t : register(t2, space1);
```

I added a test case to confirm that the register space is properly propagated through the Slang reflection API.

This change also adds proper error messages for some error/unsupported cases that weren't being diagnosed:

* Specifying a completely bogus register "class" (e.g., `register(bad99)`)
* Failing to specify a register index (`register(u)`)
* Specifying a component mask (`register(t0.x)`)
* Using `packoffset` bindings

I added test cases to cover all of these, as well as the new errors around support for register `space` bindings.

In order to get the existing tests to pass, I had to remove explicit `packoffset` bindings from some DXSDK test shaders.
None of these `packoffset` bindings were semantically significant (they matched what the compiler would do anyway, for both Slang and the standard HLSL compiler). Removing them is required for Slang now that we give an explicit error about our lack of `packoffset` support.
In a future change we might add logic to either detect semantically insignificant `packoffset`s, or to just go ahead and support them properly (as a general feature on `struct` types).

5 files changed, 51 insertions, 2 deletions

diff --git a/tests/diagnostics/gh-38-vs.hlsl.expected b/tests/diagnostics/gh-38-vs.hlsl.expected
index 05f455821..76987ae44 100644
--- a/tests/diagnostics/gh-38-vs.hlsl.expected
+++ b/tests/diagnostics/gh-38-vs.hlsl.expected
@@ -1,8 +1,8 @@
 result code = -1
 standard error = {
-tests/diagnostics/gh-38-fs.hlsl(7): error 39999: conflicting explicit bindings for parameter 'conflicting'
+tests/diagnostics/gh-38-fs.hlsl(7): error 39000: conflicting explicit bindings for parameter 'conflicting'
 tests/diagnostics/gh-38-vs.hlsl(7): note: see other declaration of 'conflicting'
-tests/diagnostics/gh-38-fs.hlsl(5): warning 39999: explicit binding for parameter 'overlappingB' overlaps with parameter 'overlappingA'
+tests/diagnostics/gh-38-fs.hlsl(5): warning 39001: explicit binding for parameter 'overlappingB' overlaps with parameter 'overlappingA'
 tests/diagnostics/gh-38-vs.hlsl(5): note: see declaration of 'overlappingA'
 }
 standard output = {
diff --git a/tests/diagnostics/packoffset.slang b/tests/diagnostics/packoffset.slang
new file mode 100644
index 000000000..31ee63bbd
--- /dev/null
+++ b/tests/diagnostics/packoffset.slang
@@ -0,0 +1,11 @@
+// packoffset.slang
+//TEST:SIMPLE:-target hlsl
+
+// use of `packoffset` (not supported):
+cbuffer B
+{
+	float4 x : packoffset(c0);
+}
+
+void main()
+{}
\ No newline at end of file
diff --git a/tests/diagnostics/packoffset.slang.expected b/tests/diagnostics/packoffset.slang.expected
new file mode 100644
index 000000000..3930fee6a
--- /dev/null
+++ b/tests/diagnostics/packoffset.slang.expected
@@ -0,0 +1,6 @@
+result code = -1
+standard error = {
+tests/diagnostics/packoffset.slang(7): error 39012: explicit 'packoffset' bindings are not yet supported in Slang
+}
+standard output = {
+}
diff --git a/tests/diagnostics/register-bindings.slang b/tests/diagnostics/register-bindings.slang
new file mode 100644
index 000000000..188d22bf5
--- /dev/null
+++ b/tests/diagnostics/register-bindings.slang
@@ -0,0 +1,22 @@
+// register-bindings.slang
+//TEST:SIMPLE:-target hlsl
+
+// Various bad forms for register bindings
+
+// Not a valid register class:
+Texture2D	a : register(DOESNT_EXIST);
+
+// No register index given:
+TextureCube b : register(t);
+
+// Unexpected name in place of `space`:
+SamplerState c : register(s0, s1);
+
+// No space index given after `space`:
+SamplerState d : register(s2, space);
+
+// use of a component mask (not supported):
+Texture2D e : register(t3.x);
+
+void main()
+{}
\ No newline at end of file
diff --git a/tests/diagnostics/register-bindings.slang.expected b/tests/diagnostics/register-bindings.slang.expected
new file mode 100644
index 000000000..04d062b10
--- /dev/null
+++ b/tests/diagnostics/register-bindings.slang.expected
@@ -0,0 +1,10 @@
+result code = -1
+standard error = {
+tests/diagnostics/register-bindings.slang(7): error 39007: unknown register class: 'DOESNT_EXIST'
+tests/diagnostics/register-bindings.slang(10): error 39008: expected a register index after 't'
+tests/diagnostics/register-bindings.slang(13): error 39009: expected 'space', got 's'
+tests/diagnostics/register-bindings.slang(16): error 39010: expected a register space index after 'space'
+tests/diagnostics/register-bindings.slang(19): error 39011: explicit register component masks are not yet supported in Slang
+}
+standard output = {
+}