SpirvShader: Optimize stores with static equal offsets

This is heavily used in dEQP-VK.ssbo.*. Avoiding generating the scatter is profitable on all non-AVX512-capable targets; ScalarizeMaskedMemIntrin is incredibly slow. Reduces runtime on dEQP-VK.ssbo.layout.random.all_shared_buffer.5 from 24s to 14s on my threadripper (on top of stack of other optimizations). Bug: b/135609394 Change-Id: I2d6840522a5bd30b4fd532b9c7e2a4712879caa9 Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/33289Tested-by: Chris Forbes <chrisforbes@google.com> Presubmit-Ready: Chris Forbes <chrisforbes@google.com> Reviewed-by: Ben Clayton <bclayton@google.com>

SpirvShader: Optimize stores with static equal offsets
cd98c739 · Chris Forbes · 61f2a46a · cd98c739
Commit cd98c739 authored Jun 22, 2019 by Chris Forbes
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SpirvShader.cpp src/Pipeline/SpirvShader.cpp +17 -0

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--- a/src/Pipeline/SpirvShader.cpp
+++ b/src/Pipeline/SpirvShader.cpp
@@ -355,6 +355,23 @@ namespace sw
 			mask &= ptr.isInBounds(sizeof(float)); // Disable OOB writes.
 			if (!atomic && order == std::memory_order_relaxed)
 			{
+				if (ptr.hasStaticEqualOffsets())
+				{
+					If (AnyTrue(mask))
+					{
+						// All equal. One of these writes will win -- elect the winning lane.
+						auto v0111 = SIMD::Int(0, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF);
+						auto elect = mask & ~(v0111 & (mask.xxyz | mask.xxxy | mask.xxxx));
+						auto maskedVal = As<SIMD::Int>(val) & elect;
+						auto scalarVal = Extract(maskedVal, 0) |
+							Extract(maskedVal, 1) |
+							Extract(maskedVal, 2) |
+							Extract(maskedVal, 3);
+						*rr::Pointer<EL>(ptr.base + ptr.staticOffsets[0], sizeof(float)) = As<EL>(scalarVal);
+					}
+					return;
+				}
+
 				if (ptr.hasStaticSequentialOffsets(sizeof(float)))
 				{
 					return rr::MaskedStore(rr::Pointer<T>(ptr.base + ptr.staticOffsets[0]), val, mask, sizeof(float));