Printf float with LLVM segfaults

Question

I am trying to call printf to print a float number from LLVM. While it works fine with int, it segfaults when using double.

Here is the code (generated from clang but slightly modified so that it works fine with llc) :

@.str = private unnamed_addr constant [3 x i8] c"%f\00", align 1

; Function Attrs: nounwind uwtable
define i32 @main() #0 {
  %1 = alloca i32, align 4
  store i32 0, i32* %1
  %2 = call i32 (i8*, ...)* @printf(i8* getelementptr inbounds ([3 x i8]* @.str, i32 0, i32 0), double 3.140000e+00)
  ret i32 0
}

declare i32 @printf(i8*, ...) #1

attributes #0 = { nounwind uwtable "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+sse,+sse2" "unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #1 = { "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+sse,+sse2" "unsafe-fp-math"="false" "use-soft-float"="false" }

Here is how I produce an executable:

llc main.ll --filetype=obj
ld -lc -e main -dynamic-linker /lib64/ld-linux-x86-64.so.2 main.o -o main

When I run main within valgrind, I get:

Process terminating with default action of signal 11 (SIGSEGV): dumping core
 General Protection Fault

I read somewhere on this site that I need to align the stack to use printf. If this is the issue, how can I do this in LLVM.

Otherwise, what is causing this segfault?

I run Linux 64-bits.

Printf float with LLVM segfaults

1 Answers