Hi,
I have a naive question on how to generate LLVM IR for inline functions. I
have compiled this C code:
*inline void func1()*
* {*
* int x=3;*
* }*
* void func2()*
* {*
* func1();*
* int y = 4;*
* }*
into LLVM IR, using
clang -emit-llvm -S -c <filename>
But the generated LLVM IR file does *not* have func1() expanded (see below
for the relevant parts).
*; Function Attrs: nounwind uwtable*
* define void @func2() #0 {*
* entry:*
* %y = alloca i32, align 4*
* call void (...)* @func1()*
* store i32 4, i32* %y, align 4*
* ret void*
* }*
* declare void @func1(...) #1*
Question: Do I need to pass some special command line options so to make
func1() expanded in the LLVM IR? Thanks.
Zhoulai
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C has weird inline semantics. Try compiling the same thing as C++ & you might get something more reasonable? On Sat, Apr 18, 2015 at 6:36 PM, Zhoulai <zell08v at gmail.com> wrote:> Hi, > > I have a naive question on how to generate LLVM IR for inline functions. I > have compiled this C code: > > inline void func1() > { > int x=3; > } > void func2() > { > func1(); > int y = 4; > > } > > into LLVM IR, using > > clang -emit-llvm -S -c <filename> > > But the generated LLVM IR file does *not* have func1() expanded (see below > for the relevant parts). > > ; Function Attrs: nounwind uwtable > define void @func2() #0 { > entry: > %y = alloca i32, align 4 > call void (...)* @func1() > store i32 4, i32* %y, align 4 > ret void > } > > declare void @func1(...) #1 > > Question: Do I need to pass some special command line options so to make > func1() expanded in the LLVM IR? Thanks. > > Zhoulai > > _______________________________________________ > LLVM Developers mailing list > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev >
> C has weird inline semantics. > > Try compiling the same thing as C++ & you might get something more > reasonable?Weird indeed. In C, an 'inline' function definition with external linkage may be ignored (the compiler may choose to treat it as an external call). Making func1() 'static inline' emits IR for func1() with the 'inlinehint' attribute; the front-end does not inline it for you. This is true for either C or C++. --paulr> > On Sat, Apr 18, 2015 at 6:36 PM, Zhoulai <zell08v at gmail.com> wrote: > > Hi, > > > > I have a naive question on how to generate LLVM IR for inline functions. > I > > have compiled this C code: > > > > inline void func1() > > { > > int x=3; > > } > > void func2() > > { > > func1(); > > int y = 4; > > > > } > > > > into LLVM IR, using > > > > clang -emit-llvm -S -c <filename> > > > > But the generated LLVM IR file does *not* have func1() expanded (see > below > > for the relevant parts). > > > > ; Function Attrs: nounwind uwtable > > define void @func2() #0 { > > entry: > > %y = alloca i32, align 4 > > call void (...)* @func1() > > store i32 4, i32* %y, align 4 > > ret void > > } > > > > declare void @func1(...) #1 > > > > Question: Do I need to pass some special command line options so to make > > func1() expanded in the LLVM IR? Thanks. > > > > Zhoulai > > > > _______________________________________________ > > LLVM Developers mailing list > > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu > > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev > > > _______________________________________________ > LLVM Developers mailing list > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev