From: Jakub Jelinek Date: Fri, 1 Dec 2023 08:25:45 +0000 (+0100) Subject: lower-bitint: Fix _BitInt .{ADD,SUB}_OVERFLOW lowering [PR112750] X-Git-Tag: basepoints/gcc-15~4097 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=364332658ef790d09d250db39c5b13e27c3543f1;p=thirdparty%2Fgcc.git lower-bitint: Fix _BitInt .{ADD,SUB}_OVERFLOW lowering [PR112750] The .{ADD,SUB}_OVERFLOW lowering is implemented by performing normal addition/subtraction (perhaps extended to even more bits than normally by continuing with extended values of operands after running of normal bits) and in addition to that trying to compute if certain sets of bits are either all zero or all sign extensions of the least significant bit. That code is in a lot of cases guarded just by a single condition (which can be idx > startlimb, idx >= startlimb or idx == startlimb) or by 2 conditions - if (idx >= startlimb) { if (idx == startlimb) ... else ... } Now, if_then_if_then_else when the second argument is NULL works just as if_then and sets m_gsi to be within the initially empty then block and that is where we emit code for constant tidx startlimb + (cmp_code == GT_EXPR). But in the 2 conditions case, m_gsi is set to the initially empty else block, so using EQ_EXPR for the condition was incorrect (and strangely nothing in the testsuite caught that), because the code for extracting the lowest set of bits (i.e. when tidx is startlimb) is then done when idx is not startlimb rather than when it is. The following patch fixes that. Note, when developing the lowering, I was using gcov to make sure all code is covered by the testsuite with minimum exceptions, so no idea how this slipped out. 2023-12-01 Jakub Jelinek PR middle-end/112750 * gimple-lower-bitint.cc (bitint_large_huge::lower_addsub_overflow): Use NE_EXPR rather than EQ_EXPR for g2 if !single_comparison and adjust probabilities. * gcc.dg/bitint-41.c: Use -std=c23 rather than -std=c2x. * gcc.dg/torture/bitint-43.c: Likewise. * gcc.dg/torture/bitint-44.c: Likewise. * gcc.dg/torture/bitint-45.c: New test. --- diff --git a/gcc/gimple-lower-bitint.cc b/gcc/gimple-lower-bitint.cc index 5024815ed9df..09eb7a34e91b 100644 --- a/gcc/gimple-lower-bitint.cc +++ b/gcc/gimple-lower-bitint.cc @@ -4028,11 +4028,11 @@ bitint_large_huge::lower_addsub_overflow (tree obj, gimple *stmt) edge edge_true_true, edge_true_false, edge_false; gimple *g2 = NULL; if (!single_comparison) - g2 = gimple_build_cond (EQ_EXPR, idx, + g2 = gimple_build_cond (NE_EXPR, idx, size_int (startlimb), NULL_TREE, NULL_TREE); if_then_if_then_else (g, g2, profile_probability::likely (), - profile_probability::unlikely (), + profile_probability::likely (), edge_true_true, edge_true_false, edge_false); unsigned tidx = startlimb + (cmp_code == GT_EXPR); diff --git a/gcc/testsuite/gcc.dg/bitint-41.c b/gcc/testsuite/gcc.dg/bitint-41.c index d87ea08bdf64..f97f03cd091c 100644 --- a/gcc/testsuite/gcc.dg/bitint-41.c +++ b/gcc/testsuite/gcc.dg/bitint-41.c @@ -1,6 +1,6 @@ /* PR middle-end/112336 */ /* { dg-do compile { target bitint } } */ -/* { dg-options "-std=c2x" } */ +/* { dg-options "-std=c23" } */ unsigned _BitInt(1) v1; unsigned _BitInt(1) *p1 = &v1; diff --git a/gcc/testsuite/gcc.dg/torture/bitint-43.c b/gcc/testsuite/gcc.dg/torture/bitint-43.c index 4265bffef706..a45f5c6b493b 100644 --- a/gcc/testsuite/gcc.dg/torture/bitint-43.c +++ b/gcc/testsuite/gcc.dg/torture/bitint-43.c @@ -1,6 +1,6 @@ /* PR c/111309 */ /* { dg-do run { target bitint } } */ -/* { dg-options "-std=c2x -pedantic-errors" } */ +/* { dg-options "-std=c23 -pedantic-errors" } */ /* { dg-skip-if "" { ! run_expensive_tests } { "*" } { "-O0" "-O2" } } */ /* { dg-skip-if "" { ! run_expensive_tests } { "-flto" } { "" } } */ diff --git a/gcc/testsuite/gcc.dg/torture/bitint-44.c b/gcc/testsuite/gcc.dg/torture/bitint-44.c index 938c0e917f34..fe5c16853878 100644 --- a/gcc/testsuite/gcc.dg/torture/bitint-44.c +++ b/gcc/testsuite/gcc.dg/torture/bitint-44.c @@ -1,6 +1,6 @@ /* PR c/111309 */ /* { dg-do run { target bitint } } */ -/* { dg-options "-std=c2x -pedantic-errors" } */ +/* { dg-options "-std=c23 -pedantic-errors" } */ /* { dg-skip-if "" { ! run_expensive_tests } { "*" } { "-O0" "-O2" } } */ /* { dg-skip-if "" { ! run_expensive_tests } { "-flto" } { "" } } */ diff --git a/gcc/testsuite/gcc.dg/torture/bitint-45.c b/gcc/testsuite/gcc.dg/torture/bitint-45.c new file mode 100644 index 000000000000..50c622d83d42 --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/bitint-45.c @@ -0,0 +1,32 @@ +/* PR middle-end/112750 */ +/* { dg-do run { target bitint } } */ +/* { dg-options "-std=c23 -pedantic-errors" } */ +/* { dg-skip-if "" { ! run_expensive_tests } { "*" } { "-O0" "-O2" } } */ +/* { dg-skip-if "" { ! run_expensive_tests } { "-flto" } { "" } } */ + +#if __BITINT_MAXWIDTH__ >= 256 +_BitInt(256) a = __INT_MAX__ + (_BitInt(256)) 1; +_BitInt(256) b = __INT_MAX__; +#endif +#if __BITINT_MAXWIDTH__ >= 512 +_BitInt(512) c = 0x7fffffffffffffffffffffffffffffffffffffffwb + (_BitInt(512)) 1; +_BitInt(512) d = 0x7fffffffffffffffffffffffffffffffffffffffwb; +#endif + +int +main () +{ +#if __BITINT_MAXWIDTH__ >= 256 + if (!__builtin_sub_overflow_p (a, 0, 0)) + __builtin_abort (); + if (!__builtin_sub_overflow_p (b, -1, 0)) + __builtin_abort (); +#endif +#if __BITINT_MAXWIDTH__ >= 512 + if (!__builtin_sub_overflow_p (c, 0, (_BitInt(160)) 0)) + __builtin_abort (); + if (!__builtin_sub_overflow_p (d, -1, 0)) + __builtin_abort (); +#endif + return 0; +}