Add support for OpAtomicISub, OpAtomicIIncrement, OpAtomicIDecrement

These are the remaining operations which were not tested through the
dEQP-VK.image.* path.

Test: dEQP-VK.spirv_assembly.*
Bug: b/127472316
Change-Id: Icedc2fc7b972714bc67705e2458e1207972b95cc
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/29457
Tested-by: Chris Forbes <chrisforbes@google.com>
Presubmit-Ready: Chris Forbes <chrisforbes@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
diff --git a/src/Reactor/Reactor.cpp b/src/Reactor/Reactor.cpp
index 43bc1d6..b2c99e2 100644
--- a/src/Reactor/Reactor.cpp
+++ b/src/Reactor/Reactor.cpp
@@ -2512,6 +2512,11 @@
 		return RValue<UInt>(Nucleus::createAtomicAdd(x.value, y.value, memoryOrder));
 	}
 
+	RValue<UInt> SubAtomic(RValue<Pointer<UInt> > x, RValue<UInt> y, std::memory_order memoryOrder)
+	{
+		return RValue<UInt>(Nucleus::createAtomicSub(x.value, y.value, memoryOrder));
+	}
+
 	RValue<UInt> AndAtomic(RValue<Pointer<UInt> > x, RValue<UInt> y, std::memory_order memoryOrder)
 	{
 		return RValue<UInt>(Nucleus::createAtomicAnd(x.value, y.value, memoryOrder));