[llvm-dev] default behavior or

[kamlesh kumar via llvm-dev]

Hi Devs,
going by this link https://llvm.org/docs/LangRef.html#floatenv
it says that floating point operation does not have side effects by
defaults.
but when compile a test case
i.e.
cat a.c
float foo(float a, float b)
{
return a+b;
}

$clang a.c -O2 -S -emit-llvm
emit ir like:
$cat a.ll
---------------------------------------
; ModuleID = 'a.c'
source_filename = "a.c"
target datalayout =
"e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

; Function Attrs: norecurse nounwind readnone uwtable
define dso_local float @foo(float %a, float %b) local_unnamed_addr #0 {
entry:
  %add = fadd float %a, %b
  ret float %add
}

attributes #0 = { norecurse nounwind readnone uwtable
"correctly-rounded-divide-sqrt-fp-math"="false"
"disable-tail-calls"="false" "frame-pointer"="none"
"less-precise-fpmad"="false" "min-legal-vector-width"="0"
"no-infs-fp-math"="false" "no-jump-tables"="false"
"no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false"
"no-trapping-math"="false" "stack-protector-buffer-size"="8"
"target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87"
"unsafe-fp-math"="false" "use-soft-float"="false" }
---------------------
and the setting "no-trapping-math"="false" should mean -ftrapping-math but
it does not and it also contradict with documentation.

I think clang should emit this "no-trapping-math"="true" by default if it
goes with this assumption  https://llvm.org/docs/LangRef.html#floatenv ?
what is default behavior of clang -fno-trapping-math or -ftrapping-math?
also clang default behavior does not match gcc?
https://godbolt.org/z/B3YvxE

./kamlesh
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