[Mesa-dev] [PATCH] radv: flush f32->f16 conversion denormals to zero.

[Dave Airlie]

From: Dave Airlie <airlied at redhat.com>

SPIR-V defines the f32->f16 operation as flushing denormals to 0,
this compares the class using amd class opcode.

Thanks to Matt Arsenault for figuring it out.

This fixes:
dEQP-VK.spirv_assembly.instruction.compute.opquantize.flush_to_zero

Signed-off-by: Dave Airlie <airlied at redhat.com>
---
 src/amd/common/ac_nir_to_llvm.c |  9 ++++++++-
 src/amd/common/sid.h            | 13 +++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/src/amd/common/ac_nir_to_llvm.c b/src/amd/common/ac_nir_to_llvm.c
index 77e3a85..ac80677 100644
--- a/src/amd/common/ac_nir_to_llvm.c
+++ b/src/amd/common/ac_nir_to_llvm.c
@@ -1027,11 +1027,18 @@ static LLVMValueRef emit_f2f16(struct nir_to_llvm_context *ctx,
 {
 	LLVMValueRef result;
 	LLVMValueRef cond;
+	LLVMValueRef args[2];
 	src0 = to_float(ctx, src0);
 	result = LLVMBuildFPTrunc(ctx->builder, src0, ctx->f16, "");
-	result = ac_build_intrinsic(&ctx->ac, "llvm.canonicalize.f16", ctx->f16, &result, 1, AC_FUNC_ATTR_READNONE);
+	LLVMValueRef mask = LLVMConstInt(ctx->i32, N_SUBNORMAL | P_SUBNORMAL, false);
+	
+	args[0] = result;
+	args[1] = mask;
+	cond = ac_build_intrinsic(&ctx->ac, "llvm.amdgcn.class.f16", ctx->i1, args, 2, AC_FUNC_ATTR_READNONE);
+
 	/* need to convert back up to f32 */
 	result = LLVMBuildFPExt(ctx->builder, result, ctx->f32, "");
+	result = LLVMBuildSelect(ctx->builder, cond, ctx->f32zero, result, "");
 	return result;
 }
 
diff --git a/src/amd/common/sid.h b/src/amd/common/sid.h
index 7789add..fa20690 100644
--- a/src/amd/common/sid.h
+++ b/src/amd/common/sid.h
@@ -9063,5 +9063,18 @@
 #define    CIK_SDMA_PACKET_SRBM_WRITE              0xe
 #define    CIK_SDMA_COPY_MAX_SIZE                  0x3fffe0
 
+enum amd_cmp_class_flags {
+	S_NAN = 1 << 0,        // Signaling NaN
+	Q_NAN = 1 << 1,        // Quiet NaN
+	N_INFINITY = 1 << 2,   // Negative infinity
+	N_NORMAL = 1 << 3,     // Negative normal
+	N_SUBNORMAL = 1 << 4,  // Negative subnormal
+	N_ZERO = 1 << 5,       // Negative zero
+	P_ZERO = 1 << 6,       // Positive zero
+	P_SUBNORMAL = 1 << 7,  // Positive subnormal
+	P_NORMAL = 1 << 8,     // Positive normal
+	P_INFINITY = 1 << 9    // Positive infinity
+};
+
 #endif /* _SID_H */
 
-- 
2.9.3