[clang] [AMDGPU][Clang] Support for type inferring extended image builtins for AMDGPU (PR #164358)

[Rana Pratap Reddy via cfe-commits]

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@@ -3,7 +3,7 @@
 
 typedef int int4 __attribute__((ext_vector_type(4)));
 typedef float float4 __attribute__((ext_vector_type(4)));
-typedef half half4 __attribute__((ext_vector_type(4)));
+typedef _Float16 half4 __attribute__((ext_vector_type(4)));
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ranapratap55 wrote:

TARGET_BUILTIN(__builtin_amdgcn_image_sample_lz_1d_v4f16_f32, "`V4x`ifQtV4ibii", "nc", "extended-image-insts")

we are using builtin def as "x", I think we cannot test "h" and "y" with it. We need to write separate def for each one of those which results in code duplication for openCL types. isn't it? @shiltian @yxsamliu @arsenm 

https://github.com/llvm/llvm-project/pull/164358