Add a compile-time loop construct to Slang

The basic syntax is:

    $for(i in Range(0,99))
    {
       /* stuff goes here */
    }

Note that the exact form is very restrictive. All that you are allowed to change is `i`, `0`, `99` or `/* stuff goes here */`.

As a tiny bit of syntax sugar, the following should work:

    $for(i in Range(99))
    {
       /* stuff goes here */
    }

Note that the range given is half-open (C++ iterator `[begin,end)` style).
Both the beginning and end of the range must be compile-time constant expressions that Slang knows how to constant-fold.

The implementation will basically generate code for `/* stuff goes here */` N times, once for each value in the half-open range.
Each time, the variable `i` will be replaced with a different compile-time-constant expression.

While I was working on a test case for this, I also found that our build of glslang had an issue with resource limits, so I fixed that.
Clients will need to build a new glslang to use the fix.

1 files changed, 14 insertions, 0 deletions

diff --git a/tests/cross-compile/compile-time-loop.slang b/tests/cross-compile/compile-time-loop.slang
new file mode 100644
index 000000000..aae35f09e
--- /dev/null
+++ b/tests/cross-compile/compile-time-loop.slang
@@ -0,0 +1,14 @@
+//TEST:CROSS_COMPILE: -profile ps_5_0 -entry main -target spirv-assembly
+
+Texture2D t;
+SamplerState s;
+
+float4 main(float2 uv) : SV_Target
+{
+	float4 result = 0;
+	$for(i in Range(0,5))
+	{
+		result += t.Sample(s, uv, int2(i - 2, 0));
+	}
+	return result;
+}