At the moment the ECF_* flags for a gimple call to a built-in function are derived from the function decl, which in turn is derived from the global command-line options. So if the compiler is run with -fno-math-errno, we always assume functions don't set errno, regardless of local optimization options. Similarly if the compiler is run with -fmath-errno, we always assume functions set errno.
This shows up in gcc.dg/lto/20110201-1_0.c, where we compile the file with -O0 and use -O2 -ffast-math for a specific function. -O2 -ffast-math is enough for us to convert cabs to sqrt as hoped, but because of the global -fmath-errno setting, we assume that the call to sqrt is not pure or const and create vops for it. This makes it appear to the gimple code that a simple sqrt optab isn't enough. Later patches move more decisions about maths functions to gimple and think that in this case we should use: y = sqrt (x); if (!(x >= 0)) sqrt (x); // to set errno. This is being tracked as PR68235. For now the patch adds -fno-math-errno to the dg-options for this test. Tested on x86_64-linux-gnu, aarch64-linux-gnu and arm-linux-gnueabi. OK to install? Thanks, Richard gcc/testsuite/ PR tree-optimization/68235 * gcc.dg/lto/20110201-1_0.c: Add -fno-math-errno. diff --git a/gcc/testsuite/gcc.dg/lto/20110201-1_0.c b/gcc/testsuite/gcc.dg/lto/20110201-1_0.c index 068dddc..2144f07 100644 --- a/gcc/testsuite/gcc.dg/lto/20110201-1_0.c +++ b/gcc/testsuite/gcc.dg/lto/20110201-1_0.c @@ -1,6 +1,6 @@ /* { dg-lto-do run } */ -/* { dg-lto-options { { -O0 -flto } } } */ -/* { dg-lto-options { "-O0 -flto -mfloat-abi=softfp -mfpu=neon-vfpv4" } { target arm*-*-* } } */ +/* { dg-lto-options { { -O0 -flto -fno-math-errno } } } */ +/* { dg-lto-options { "-O0 -flto -fno-math-errno -mfloat-abi=softfp -mfpu=neon-vfpv4" } { target arm*-*-* } } */ /* { dg-require-linker-plugin "" } */ /* { dg-require-effective-target sqrt_insn } */