From bae12c6b74c5c216e25e9fc5cf655ad3060be558 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Samuel=20Iglesias=20Gons=C3=A1lvez?= <siglesias@igalia.com>
Date: Tue, 4 Dec 2018 16:22:26 +0100
Subject: [PATCH] Add precision error margin to cos() tests for float_controls
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On some old Intel hardware, Mesa doesn't return exactly 1.0 for cos(0).
This change implements the precision error margin for the affected cos() tests,
following Vulkan spec, "Precision and Operation of SPIR-V Instructions".

Components: Vulkan

Affects: dEQP-VK.spirv_assembly.instruction.*.float_controls.*.cos_denorm_flush_to_zero*

VK-GL-CTS issue: 1498

Change-Id: I2ff07616f706d4214517917276aeb26d2d875325
Signed-off-by: Samuel Iglesias Gonsálvez <siglesias@igalia.com>
---
 .../spirv_assembly/vktSpvAsmFloatControlsTests.cpp | 25 ++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/external/vulkancts/modules/vulkan/spirv_assembly/vktSpvAsmFloatControlsTests.cpp b/external/vulkancts/modules/vulkan/spirv_assembly/vktSpvAsmFloatControlsTests.cpp
index 7edc90f..5a1a358 100644
--- a/external/vulkancts/modules/vulkan/spirv_assembly/vktSpvAsmFloatControlsTests.cpp
+++ b/external/vulkancts/modules/vulkan/spirv_assembly/vktSpvAsmFloatControlsTests.cpp
@@ -113,6 +113,7 @@ enum ValueId
 	V_ZERO_OR_FP32_DENORM_TO_FP64,
 	V_DENORM_TIMES_TWO,
 	V_DEGREES_DENORM,
+	V_TRIG_ONE,			//  1.0 trigonometric operations, including precision margin
 
 	//results of conversion operations
 	V_CONV_TO_FP16_RTZ_RESULT,
@@ -901,7 +902,7 @@ TypeTestResults<deFloat16>::TypeTestResults()
 		{ O_RADIANS,		V_ZERO },
 		{ O_DEGREES,		V_ZERO },
 		{ O_SIN,			V_ZERO },
-		{ O_COS,			V_ONE },
+		{ O_COS,			V_TRIG_ONE },
 		{ O_TAN,			V_ZERO },
 		{ O_ASIN,			V_ZERO },
 		{ O_ACOS,			V_PI_DIV_2 },
@@ -1029,7 +1030,7 @@ TypeTestResults<float>::TypeTestResults()
 		{ O_RADIANS,		V_ZERO },
 		{ O_DEGREES,		V_ZERO },
 		{ O_SIN,			V_ZERO },
-		{ O_COS,			V_ONE },
+		{ O_COS,			V_TRIG_ONE },
 		{ O_TAN,			V_ZERO },
 		{ O_ASIN,			V_ZERO },
 		{ O_ACOS,			V_PI_DIV_2 },
@@ -2006,6 +2007,22 @@ bool isAcosResultCorrect(const TYPE& returnedFloat, TestLog& log)
 	return false;
 }
 
+template <typename TYPE>
+bool isCosResultCorrect(const TYPE& returnedFloat, TestLog& log)
+{
+	// for cos(x) with x between -pi and pi, the precision error is 2^-11 for fp32 and 2^-7 for fp16.
+	double precision = returnedFloat.MANTISSA_BITS == 23 ? dePow(2, -11) : dePow(2, -7);
+	const double expected = 1.0;
+
+	if (deAbs(returnedFloat.asDouble() - expected) < precision)
+		return true;
+
+	log << TestLog::Message << "Expected result to be in range"
+		<< " (" << expected - precision << ", " << expected + precision << "), got "
+		<< returnedFloat.asDouble() << TestLog::EndMessage;
+	return false;
+}
+
 // Function used to compare test result with expected output.
 // TYPE can be Float16, Float32 or Float64.
 // FLOAT_TYPE can be deFloat16, float, double.
@@ -2076,6 +2093,10 @@ bool compareBytes(vector<deUint8>& expectedBytes, AllocationSp outputAlloc, Test
 		return (returnedValue == 0xbc00) || (returnedValue == 0xbbff);
 	}
 
+	// handle trigonometric operations precision errors
+	if (expectedValueId == V_TRIG_ONE)
+		return isCosResultCorrect<TYPE>(returnedFloat, log);
+
 	// handle acos(0) case
 	if (expectedValueId == V_PI_DIV_2)
 		return isAcosResultCorrect<TYPE>(returnedFloat, log);
-- 
2.7.4