commit f6640761c46b42a996925de407c52295f3b3f6f0
author John Kessenich <cepheus@frii.com> Mon Aug 01 19:44:00 2016 -0600
committer John Kessenich <cepheus@frii.com> Tue Aug 02 21:48:02 2016 -0600
tree 7a0d1b0754950187a0734a42194100794fc5d21e
parent 6c136223ed31a2e2f761af55180f26ba6622599d

Front-end: Implement 2nd task of issue #400; precision of result and operation.

From the ES spec + Bugzilla 15931 and GL_KHR_vulkan_glsl:
- Update precision qualifiers for all built-in function prototypes.
- Implement the new algorithm used to distinguish built-in function
  operation precisions from result precisions.
Also add tracking of separate result and operation precisions, and
use that in generating SPIR-V.
(SPIR-V cares about precision of operation, while the front-end
cares about precision of result, for propagation.)

SPIRV/GlslangToSpv.cpp

diff --git a/SPIRV/GlslangToSpv.cpp b/SPIRV/GlslangToSpv.cpp
index be266ac..6aec9e6 100755
--- a/SPIRV/GlslangToSpv.cpp
+++ b/SPIRV/GlslangToSpv.cpp
@@ -283,10 +283,10 @@
     }
 }
 
-// Translate glslang type to SPIR-V precision decorations.
-spv::Decoration TranslatePrecisionDecoration(const glslang::TType& type)
+// Translate glslang precision to SPIR-V precision decorations.
+spv::Decoration TranslatePrecisionDecoration(glslang::TPrecisionQualifier glslangPrecision)
 {
-    switch (type.getQualifier().precision) {
+    switch (glslangPrecision) {
     case glslang::EpqLow:    return spv::DecorationRelaxedPrecision;
     case glslang::EpqMedium: return spv::DecorationRelaxedPrecision;
     default:
@@ -294,6 +294,12 @@
     }
 }
 
+// Translate glslang type to SPIR-V precision decorations.
+spv::Decoration TranslatePrecisionDecoration(const glslang::TType& type)
+{
+    return TranslatePrecisionDecoration(type.getQualifier().precision);
+}
+
 // Translate glslang type to SPIR-V block decorations.
 spv::Decoration TranslateBlockDecoration(const glslang::TType& type)
 {
@@ -940,7 +946,7 @@
                 spv::Id leftRValue = accessChainLoad(node->getLeft()->getType());
 
                 // do the operation
-                rValue = createBinaryOperation(node->getOp(), TranslatePrecisionDecoration(node->getType()),
+                rValue = createBinaryOperation(node->getOp(), TranslatePrecisionDecoration(node->getOperationPrecision()),
                                                TranslateNoContractionDecoration(node->getType().getQualifier()),
                                                convertGlslangToSpvType(node->getType()), leftRValue, rValue,
                                                node->getType().getBasicType());
@@ -1065,7 +1071,7 @@
     spv::Id right = accessChainLoad(node->getRight()->getType());
 
     // get result
-    spv::Id result = createBinaryOperation(node->getOp(), TranslatePrecisionDecoration(node->getType()),
+    spv::Id result = createBinaryOperation(node->getOp(), TranslatePrecisionDecoration(node->getOperationPrecision()),
                                            TranslateNoContractionDecoration(node->getType().getQualifier()),
                                            convertGlslangToSpvType(node->getType()), left, right,
                                            node->getLeft()->getType().getBasicType());
@@ -1142,7 +1148,7 @@
     else
         operand = accessChainLoad(node->getOperand()->getType());
 
-    spv::Decoration precision = TranslatePrecisionDecoration(node->getType());
+    spv::Decoration precision = TranslatePrecisionDecoration(node->getOperationPrecision());
     spv::Decoration noContraction = TranslateNoContractionDecoration(node->getType().getQualifier());
 
     // it could be a conversion
@@ -1187,7 +1193,7 @@
             else
                 op = glslang::EOpSub;
 
-            spv::Id result = createBinaryOperation(op, TranslatePrecisionDecoration(node->getType()),
+            spv::Id result = createBinaryOperation(op, precision,
                                                    TranslateNoContractionDecoration(node->getType().getQualifier()),
                                                    convertGlslangToSpvType(node->getType()), operand, one,
                                                    node->getType().getBasicType());
@@ -1249,7 +1255,7 @@
 
     assert(node->getOp());
 
-    spv::Decoration precision = TranslatePrecisionDecoration(node->getType());
+    spv::Decoration precision = TranslatePrecisionDecoration(node->getOperationPrecision());
 
     switch (node->getOp()) {
     case glslang::EOpSequence:
@@ -2573,7 +2579,7 @@
         translateArguments(*node->getAsAggregate(), arguments);
     else
         translateArguments(*node->getAsUnaryNode(), arguments);
-    spv::Decoration precision = TranslatePrecisionDecoration(node->getType());
+    spv::Decoration precision = TranslatePrecisionDecoration(node->getOperationPrecision());
 
     spv::Builder::TextureParameters params = { };
     params.sampler = arguments[0];