On Wed, Feb 20, 2019 at 10:13 PM Arnd Bergmann <arnd@xxxxxxxx> wrote: > > In the example in https://bugs.llvm.org/show_bug.cgi?id=38809#c12 > (https://godbolt.org/z/ylsGSQ) there is no inlining, yet clang uses > over ten times as much stack space as gcc, for reasons I still > can't explain. My assumption right now is that the underlying bug > causes most of the problems with excessive stack usage in > allmodconfig kernels. Here is an even more minimal example: struct s { int i[5]; } f(void); void g(void) { f(); f();} https://godbolt.org/z/d_KWkh It's clear that clang does /something/ here when asan-stack=1 is set, but I fail to see what it is, or why that is necessary. The output of clang with asan-stack=0 is the expected code, and basically identical to what gcc produces with or without asan-stack. Arnd
