[clang] [llvm] [RISCV] Add -march support for many of the S extensions mentioned in the profile specification. (PR #79399)

[Fangrui Song via cfe-commits]

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@@ -269,6 +286,142 @@
 // CHECK-M-EXT: __riscv_mul 1
 // CHECK-M-EXT: __riscv_muldiv 1
 
+// RUN: %clang --target=riscv32-unknown-linux-gnu \
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MaskRay wrote:

(For newer tests, ensure the continuation line is indented by 2 spaces)

https://github.com/llvm/llvm-project/pull/79399