[PATCH] D101640: [clang][patch] Add support for option -fextend-arguments={32,64}: widen integer arguments to int64 in unprototyped function calls

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman added inline comments.


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Comment at: clang/include/clang/Basic/LangOptions.h:262-264
+    /// Unprototyped integer arguments are extended to 32 bits.
+    ExtendTo32,
+    /// Unprototyped integer arguments are extended to 64 bits.
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The comments aren't quite right as this matters in functions with prototypes as well (due to variadic arguments). How about "integer arguments are sign or zero extended to 32/64 bits during default argument promotions."?


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Comment at: clang/include/clang/Basic/TargetInfo.h:1415
 
+  virtual bool supportsExtendIntArgs() const { return false; }
+
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This should get a comment explaining what it does. The name is a bit generic too (esp given that there's an `_ExtInt` type that sounds like an "extended int").

Is there anything truly target-specific about the functionality? It seems like this behavior would be plausibly useful regardless of target architecture. 


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Comment at: clang/include/clang/Driver/Options.td:1432-1433
+  Flags<[CC1Option, NoArgumentUnused]>,
+  HelpText<"Controls how scalar integer arguments are extended in calls"
+           " to unprototyped and varargs functions">,
+  Values<"32,64">,
----------------
It's a bit more conventional to use a trailing whitespace in adjacent string literals.


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Comment at: clang/test/CodeGen/extend-arg-64.c:19
+
+int vararg(int, ...);
+
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Can you also add a test for K&R C functions? e.g., `int knr();` `sum = knr(sum, u32, s32, u16, s16, u8, s8);`

Also, can you show what happens when passing a `long long` and an `_ExtInt`


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  https://reviews.llvm.org/D101640/new/

https://reviews.llvm.org/D101640