[PATCH] D159069: [builtins] Fix signed integer overflows in fp_fixint_impl.inc

Fangrui Song via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Thu Aug 31 00:21:02 PDT 2023

MaskRay added inline comments.

Comment at: compiler-rt/test/builtins/Unit/fixsfdi_test.c:73
-   return 0;
+    if (test__fixsfdi(-0x8000000000000000.0p+0F, 0x8000000000000000LL))
+      return 1;
Ka-Ka wrote:
> MaskRay wrote:
> > Ka-Ka wrote:
> > > The added test pass when compiling with gcc -lgcc.
> > > 
> > This checks the `__fixunssfdi` code path, not `fp_fixint_impl.inc`.
> It turn out that the added test only trigger the intended case if compiler-rt is compiled with `-D__SOFTFP__` (which we do in our out of tree target). Maybe it is impossible to trigger the signed overflow in fp_fixint_impl.inc in a in tree target (ARM seems to have a feature for softfp but probably not enabled when compiling compiler-rt?).
> Should I simply remove the added test from the patch as it don't trigger the intended case?
should be fine to keep it...

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