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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/105338] [12 Regression] Regression: jump or cmove generated for pattern (x ? CST : 0) Date: Fri, 22 Apr 2022 12:28:20 +0000 [thread overview] Message-ID: <bug-105338-4-HFzKNeKxKJ@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-105338-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105338 --- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> --- --- gcc/config/i386/i386-expand.cc.jj 2022-04-13 15:42:39.000000000 +0200 +++ gcc/config/i386/i386-expand.cc 2022-04-22 14:18:27.347135185 +0200 @@ -3136,6 +3136,8 @@ ix86_expand_int_movcc (rtx operands[]) bool sign_bit_compare_p = false; rtx op0 = XEXP (operands[1], 0); rtx op1 = XEXP (operands[1], 1); + rtx op2 = operands[2]; + rtx op3 = operands[3]; if (GET_MODE (op0) == TImode || (GET_MODE (op0) == DImode @@ -3153,17 +3155,29 @@ ix86_expand_int_movcc (rtx operands[]) || (op1 == constm1_rtx && (code == GT || code == LE))) sign_bit_compare_p = true; + /* op0 == op1 ? op0 : op3 is equivalent to op0 == op1 ? op1 : op3, + but if op1 is a constant, the latter form allows more optimizations, + either through the last 2 ops being constant handling, or the one + constant and one variable cases. On the other side, for cmov the + former might be better as we don't need to load the constant into + another register. */ + if (code == EQ && CONST_INT_P (op1) && rtx_equal_p (op0, op2)) + op2 = op1; + /* Similarly for op0 != op1 ? op2 : op0 and op0 != op1 ? op2 : op1. */ + else if (code == NE && CONST_INT_P (op1) && rtx_equal_p (op0, op3)) + op3 = op1; + /* Don't attempt mode expansion here -- if we had to expand 5 or 6 HImode insns, we'd be swallowed in word prefix ops. */ if ((mode != HImode || TARGET_FAST_PREFIX) && (mode != (TARGET_64BIT ? TImode : DImode)) - && CONST_INT_P (operands[2]) - && CONST_INT_P (operands[3])) + && CONST_INT_P (op2) + && CONST_INT_P (op3)) { rtx out = operands[0]; - HOST_WIDE_INT ct = INTVAL (operands[2]); - HOST_WIDE_INT cf = INTVAL (operands[3]); + HOST_WIDE_INT ct = INTVAL (op2); + HOST_WIDE_INT cf = INTVAL (op3); HOST_WIDE_INT diff; diff = ct - cf; @@ -3559,6 +3573,9 @@ ix86_expand_int_movcc (rtx operands[]) if (BRANCH_COST (optimize_insn_for_speed_p (), false) <= 2) return false; + operands[2] = op2; + operands[3] = op3; + /* If one of the two operands is an interesting constant, load a constant with the above and mask it in with a logical operation. */ fixes the first and last 2 functions, now to look what's going on with the second and third one...
next prev parent reply other threads:[~2022-04-22 12:28 UTC|newest] Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-04-21 17:47 [Bug rtl-optimization/105338] New: " denis.campredon at gmail dot com 2022-04-22 6:13 ` [Bug rtl-optimization/105338] [12 Regression] " rguenth at gcc dot gnu.org 2022-04-22 9:17 ` jakub at gcc dot gnu.org 2022-04-22 9:48 ` pinskia at gcc dot gnu.org 2022-04-22 11:00 ` jakub at gcc dot gnu.org 2022-04-22 11:11 ` rguenth at gcc dot gnu.org 2022-04-22 11:14 ` rguenth at gcc dot gnu.org 2022-04-22 11:20 ` rguenth at gcc dot gnu.org 2022-04-22 12:28 ` jakub at gcc dot gnu.org [this message] 2022-04-22 13:59 ` jakub at gcc dot gnu.org 2022-04-22 14:11 ` jakub at gcc dot gnu.org 2022-04-22 14:24 ` [Bug target/105338] " jakub at gcc dot gnu.org 2022-04-23 8:26 ` cvs-commit at gcc dot gnu.org 2022-04-25 14:48 ` jakub at gcc dot gnu.org 2022-04-26 5:05 ` denis.campredon at gmail dot com 2022-04-26 8:21 ` jakub at gcc dot gnu.org
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