From 7590d975ecfdae4f112b5086c017101c08f07e3e Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Mon, 8 Jan 2024 13:57:26 +0100 Subject: [PATCH] lower-bitint: Punt .*_OVERFLOW optimization if cast from IMAGPART_EXPR appears before REALPART_EXPR [PR113119] _BitInt lowering for .{ADD,SUB,MUL}_OVERFLOW calls which have both REALPART_EXPR and IMAGPART_EXPR used and have a cast from the IMAGPART_EXPR to a boolean or normal integral type lowers them at the point of the REALPART_EXPR statement (which is especially needed if the lhs of the call is complex with large/huge _BitInt element type); we emit the stmt to set the lhs of the cast at the same spot as well. Normally, the lowering of __builtin_{add,sub,mul}_overflow arranges the REALPART_EXPR to come before IMAGPART_EXPR, followed by cast from that, but as the testcase shows, a redundant __builtin_*_overflow call and VN can reorder those and we then ICE because the def-stmt of the former cast from IMAGPART_EXPR may appear after its uses. We already check that all of REALPART_EXPR, IMAGPART_EXPR and the cast from the latter appear in the same bb as the .{ADD,SUB,MUL}_OVERFLOW call in the optimization, the following patch just extends it to make sure cast appears after REALPART_EXPR; if not, we punt on the optimization and expand it as a store of a complex _BitInt on the location of the ifn call. Only the testcase in the testsuite is changed by the patch, all other __builtin_*_overflow* calls in the bitint* tests (and there are quite a few) have REALPART_EXPR first. 2024-01-08 Jakub Jelinek PR tree-optimization/113119 * gimple-lower-bitint.cc (optimizable_arith_overflow): Punt if both REALPART_EXPR and cast from IMAGPART_EXPR appear, but cast is before REALPART_EXPR. * gcc.dg/bitint-61.c: New test. --- gcc/gimple-lower-bitint.cc | 26 +++++++++++++++++++++++++- gcc/testsuite/gcc.dg/bitint-61.c | 17 +++++++++++++++++ 2 files changed, 42 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/gcc.dg/bitint-61.c diff --git a/gcc/gimple-lower-bitint.cc b/gcc/gimple-lower-bitint.cc index 9a80f9345843..3869a1649925 100644 --- a/gcc/gimple-lower-bitint.cc +++ b/gcc/gimple-lower-bitint.cc @@ -305,6 +305,7 @@ optimizable_arith_overflow (gimple *stmt) imm_use_iterator ui; use_operand_p use_p; int seen = 0; + gimple *realpart = NULL, *cast = NULL; FOR_EACH_IMM_USE_FAST (use_p, ui, lhs) { gimple *g = USE_STMT (use_p); @@ -317,6 +318,7 @@ optimizable_arith_overflow (gimple *stmt) if ((seen & 1) != 0) return 0; seen |= 1; + realpart = g; } else if (gimple_assign_rhs_code (g) == IMAGPART_EXPR) { @@ -338,13 +340,35 @@ optimizable_arith_overflow (gimple *stmt) if (!INTEGRAL_TYPE_P (TREE_TYPE (lhs2)) || TREE_CODE (TREE_TYPE (lhs2)) == BITINT_TYPE) return 0; + cast = use_stmt; } else return 0; } if ((seen & 2) == 0) return 0; - return seen == 3 ? 2 : 1; + if (seen == 3) + { + /* Punt if the cast stmt appears before realpart stmt, because + if both appear, the lowering wants to emit all the code + at the location of realpart stmt. */ + gimple_stmt_iterator gsi = gsi_for_stmt (realpart); + unsigned int cnt = 0; + do + { + gsi_prev_nondebug (&gsi); + if (gsi_end_p (gsi) || gsi_stmt (gsi) == cast) + return 0; + if (gsi_stmt (gsi) == stmt) + return 2; + /* If realpart is too far from stmt, punt as well. + Usually it will appear right after it. */ + if (++cnt == 32) + return 0; + } + while (1); + } + return 1; } /* If STMT is some kind of comparison (GIMPLE_COND, comparison assignment) diff --git a/gcc/testsuite/gcc.dg/bitint-61.c b/gcc/testsuite/gcc.dg/bitint-61.c new file mode 100644 index 000000000000..2b2708ade238 --- /dev/null +++ b/gcc/testsuite/gcc.dg/bitint-61.c @@ -0,0 +1,17 @@ +/* PR tree-optimization/113119 */ +/* { dg-do compile { target bitint } } */ +/* { dg-options "-std=c23 -O2" } */ + +_BitInt(8) b; +_Bool c; +#if __BITINT_MAXWIDTH__ >= 8445 +_BitInt(8445) a; + +void +foo (_BitInt(4058) d) +{ + c = __builtin_add_overflow (a, 0ULL, &d); + __builtin_add_overflow (a, 0ULL, &d); + b = d; +} +#endif -- 2.47.2