SpirvShader: Implement GLSLstd450Tanh

Bug: b/126873455
Tests: dEQP-VK.glsl.builtin.precision.tanh.*
Change-Id: If63f53b5d9d78dd4a2cd6c31c42cb16f03a48d98
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/28691
Tested-by: Ben Clayton <bclayton@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
diff --git a/src/Reactor/LLVMReactor.cpp b/src/Reactor/LLVMReactor.cpp
index d41cb0e..aebcfd6 100644
--- a/src/Reactor/LLVMReactor.cpp
+++ b/src/Reactor/LLVMReactor.cpp
@@ -561,6 +561,7 @@
 			func_.emplace("atanf", reinterpret_cast<void*>(atanf));
 			func_.emplace("sinhf", reinterpret_cast<void*>(sinhf));
 			func_.emplace("coshf", reinterpret_cast<void*>(coshf));
+			func_.emplace("tanhf", reinterpret_cast<void*>(tanhf));
 
 #ifdef __APPLE__
 			// LLVM uses this function on macOS for tan.
@@ -3132,6 +3133,11 @@
 		return TransformFloat4PerElement(v, "coshf");
 	}
 
+	RValue<Float4> Tanh(RValue<Float4> v)
+	{
+		return TransformFloat4PerElement(v, "tanhf");
+	}
+
 	Type *Float4::getType()
 	{
 		return T(llvm::VectorType::get(T(Float::getType()), 4));