Accumulate compile-time constant and runtime offsets separately

This makes WalkAccessChain slightly easier on the backend -- there is
less constant folding to do.

Bug: b/124388146

Change-Id: I4e76c3e494278e1399b8a86134b652c2a6d96d8c
Reviewed-on: https://swiftshader-review.googlesource.com/c/24988
Tested-by: Chris Forbes <chrisforbes@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>

diff --git a/src/Pipeline/SpirvShader.cpp b/src/Pipeline/SpirvShader.cpp
index 87dfbf2..c9bd086 100644 (file)
--- a/src/Pipeline/SpirvShader.cpp
+++ b/src/Pipeline/SpirvShader.cpp
@@ -493,12 +493,13 @@ namespace sw
                // TODO: think about explicit layout (UBO/SSBO) storage classes
                // TODO: avoid doing per-lane work in some cases if we can?
 
-               Int4 res = Int4(0);
+               int constantOffset = 0;
+               Int4 dynamicOffset = Int4(0);
                auto & baseObject = getObject(id);
                auto typeId = baseObject.definition.word(1);
 
                if (baseObject.kind == Object::Kind::Value)
-                       res += As<Int4>(routine->getValue(id)[0]);
+                       dynamicOffset += As<Int4>(routine->getValue(id)[0]);
 
                for (auto i = 0u; i < numIndexes; i++)
                {
@@ -512,7 +513,7 @@ namespace sw
                                for (auto j = 0; j < memberIndex; j++) {
                                        offsetIntoStruct += getType(type.definition.word(2 + memberIndex)).sizeInComponents;
                                }
-                               res += Int4(offsetIntoStruct);
+                               constantOffset += offsetIntoStruct;
                                break;
                        }
 
@@ -523,9 +524,9 @@ namespace sw
                                auto stride = getType(type.definition.word(2)).sizeInComponents;
                                auto & obj = getObject(indexIds[i]);
                                if (obj.kind == Object::Kind::Constant)
-                                       res += Int4(stride * GetConstantInt(indexIds[i]));
+                                       constantOffset += stride * GetConstantInt(indexIds[i]);
                                else
-                                       res += Int4(stride) * As<Int4>(routine->getValue(indexIds[i])[0]);
+                                       dynamicOffset += Int4(stride) * As<Int4>(routine->getValue(indexIds[i])[0]);
                                break;
                        }
 
@@ -534,7 +535,7 @@ namespace sw
                        }
                }
 
-               return res;
+               return dynamicOffset + Int4(constantOffset);
        }
 
        void SpirvShader::Decorations::Apply(spv::Decoration decoration, uint32_t arg)