math_brute_force: stop relying on volatile for IsTininessDetectedBefo…

…reRounding (#2038)

This makes it literally impossible for drivers to constant fold the
IsTininessDetectedBeforeRounding kernel. Sure, drivers might have should
respect volatile here, but I'm not convinced this is actually required
by the spec in a very strict sense, because here there are no
side-effects possible in the first place.

And as far as I know, constant folding is allowed to give different
results than an actual GPU calculation would.

In any case, passing the constants via kernel arguments makes this
detection more reliable and one doesn't have to wonder why the fma test
is failing.

Side note: this was the last bug (known as of today) I had to fix in
order being able to make a CL CTS submission for Apple Silicon devices.

test_conformance/math_brute_force/main.cpp

@@ -1043,13 +1043,14 @@ int IsTininessDetectedBeforeRounding(void)
 {
  int error;
  const char *kernelSource =
- R"(__kernel void IsTininessDetectedBeforeRounding( __global float *out )
+ R"(__kernel void IsTininessDetectedBeforeRounding( __global float *out, float a, float b )
  {
- volatile float a = 0x1.000002p-126f;
- volatile float b = 0x1.fffffcp-1f;
  out[0] = a * b; // product is 0x1.fffffffffff8p-127
  })";
 
+ float a = 0x1.000002p-126f;
+ float b = 0x1.fffffcp-1f;
+
  clProgramWrapper query;
  clKernelWrapper kernel;
  error =
@@ -1073,6 +1074,22 @@ int IsTininessDetectedBeforeRounding(void)
  return error;
  }
 
+ if ((error = clSetKernelArg(kernel, 1, sizeof(a), &a)))
+ {
+ vlog_error("Error: Unable to set kernel arg to detect how tininess is "
+ "detected for the device. Err = %d",
+ error);
+ return error;
+ }
+
+ if ((error = clSetKernelArg(kernel, 2, sizeof(b), &b)))
+ {
+ vlog_error("Error: Unable to set kernel arg to detect how tininess is "
+ "detected for the device. Err = %d",
+ error);
+ return error;
+ }
+
  size_t dim = 1;
  if ((error = clEnqueueNDRangeKernel(gQueue, kernel, 1, NULL, &dim, NULL, 0,
  NULL, NULL)))