[clang] [llvm] Clang: convert `__m64` intrinsics to unconditionally use SSE2 instead of MMX. (PR #96540)

[James Y Knight via cfe-commits]

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@@ -0,0 +1,29 @@
+USE_XMM=
+#USE_XMM=--use-xmm
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jyknight wrote:

It works if you first delete/ifdef-out test_stores and test_maskmove. I didn't make those generic.

(The "USE_XMM" version is to validate that the unused bits of the input xmm registers being set to arbitrary values won't cause trouble, since some of the instructions trigger side-effects, like floating-point exception flags being set.)

https://github.com/llvm/llvm-project/pull/96540