From: Roger Sayle Date: Tue, 14 Dec 2004 01:47:30 +0000 (+0000) Subject: re PR target/18002 ('while' loop performace regression on avr target) X-Git-Tag: releases/gcc-3.4.4~419 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=05392fb4f9bcf85a5636ab1a321617f9ccd0407f;p=thirdparty%2Fgcc.git re PR target/18002 ('while' loop performace regression on avr target) PR target/18002 PR middle-end/18424 Backport from mainline 2004-03-20 Richard Sandiford * Makefile.in (dojump.o): Depend on $(GGC_H) and dojump.h. (GTFILES): Add $(srcdir)/dojump.h. (gt-dojump.h): New dependency. * dojump.c (and_reg, and_test, shift_test): New static variables. (prefer_and_bit_test): New function. (do_jump): Use it to choose between (X & (1 << C)) and (X >> C) & 1. 2004-03-21 Andrew Pinski * dojump.c (prefer_and_bit_test): Fix which part of the and_test is replaced. 2004-12-10 Roger Sayle * dojump.c (do_jump): When attempting to reverse the effects of fold_single_bit_test, we need to STRIP_NOPS and narrowing type conversions, and handle BIT_XOR_EXPR that's used to invert the sense of the single bit test. From-SVN: r92117 --- diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 473ea11cf432..69f600a99ef5 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,27 @@ +2004-12-13 Roger Sayle + + PR target/18002 + PR middle-end/18424 + Backport from mainline + + 2004-03-20 Richard Sandiford + * Makefile.in (dojump.o): Depend on $(GGC_H) and dojump.h. + (GTFILES): Add $(srcdir)/dojump.h. + (gt-dojump.h): New dependency. + * dojump.c (and_reg, and_test, shift_test): New static variables. + (prefer_and_bit_test): New function. + (do_jump): Use it to choose between (X & (1 << C)) and (X >> C) & 1. + + 2004-03-21 Andrew Pinski + * dojump.c (prefer_and_bit_test): Fix which part of + the and_test is replaced. + + 2004-12-10 Roger Sayle + * dojump.c (do_jump): When attempting to reverse the effects of + fold_single_bit_test, we need to STRIP_NOPS and narrowing type + conversions, and handle BIT_XOR_EXPR that's used to invert the + sense of the single bit test. + 2004-12-13 Richard Henderson PR middle-end/17930 diff --git a/gcc/Makefile.in b/gcc/Makefile.in index 46f5619f87be..4f8307dcb20e 100644 --- a/gcc/Makefile.in +++ b/gcc/Makefile.in @@ -1595,7 +1595,7 @@ expr.o : expr.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_H) $(TREE_H) f except.h reload.h $(GGC_H) langhooks.h intl.h $(TM_P_H) real.h $(TARGET_H) dojump.o : dojump.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_H) $(TREE_H) \ flags.h function.h $(EXPR_H) $(OPTABS_H) $(INSN_ATTR_H) insn-config.h \ - langhooks.h + langhooks.h $(GGC_H) gt-dojump.h builtins.o : builtins.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_H) $(TREE_H)\ flags.h $(TARGET_H) function.h $(REGS_H) $(EXPR_H) $(OPTABS_H) insn-config.h \ $(RECOG_H) output.h typeclass.h hard-reg-set.h toplev.h hard-reg-set.h \ @@ -2077,6 +2077,7 @@ GTFILES = $(srcdir)/input.h $(srcdir)/coretypes.h $(srcdir)/cpplib.h \ $(srcdir)/c-common.h $(srcdir)/c-tree.h \ $(srcdir)/alias.c $(srcdir)/bitmap.c $(srcdir)/cselib.c $(srcdir)/cgraph.c \ $(srcdir)/dbxout.c $(srcdir)/dwarf2out.c $(srcdir)/dwarf2asm.c \ + $(srcdir)/dojump.c \ $(srcdir)/emit-rtl.c $(srcdir)/except.c $(srcdir)/explow.c $(srcdir)/expr.c \ $(srcdir)/fold-const.c $(srcdir)/function.c \ $(srcdir)/gcse.c $(srcdir)/integrate.c $(srcdir)/lists.c $(srcdir)/optabs.c \ @@ -2096,7 +2097,7 @@ gt-cgraph.h gt-coverage.h gtype-desc.h gtype-desc.c gt-except.h \ gt-function.h gt-integrate.h gt-stmt.h gt-tree.h gt-varasm.h \ gt-emit-rtl.h gt-explow.h gt-stor-layout.h gt-regclass.h \ gt-lists.h gt-alias.h gt-cselib.h gt-fold-const.h gt-gcse.h \ -gt-expr.h gt-sdbout.h gt-optabs.h gt-bitmap.h \ +gt-expr.h gt-sdbout.h gt-optabs.h gt-bitmap.h gt-dojump.h \ gt-dwarf2out.h gt-ra-build.h gt-reg-stack.h gt-dwarf2asm.h \ gt-dbxout.h gt-c-common.h gt-c-decl.h gt-c-parse.h \ gt-c-pragma.h gtype-c.h gt-input.h gt-cfglayout.h \ diff --git a/gcc/dojump.c b/gcc/dojump.c index f3b8928e0780..b232576d440e 100644 --- a/gcc/dojump.c +++ b/gcc/dojump.c @@ -1,6 +1,6 @@ /* Convert tree expression to rtl instructions, for GNU compiler. Copyright (C) 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, - 2000, 2001, 2002, 2003 Free Software Foundation, Inc. + 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc. This file is part of GCC. @@ -33,7 +33,9 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA #include "expr.h" #include "optabs.h" #include "langhooks.h" +#include "ggc.h" +static bool prefer_and_bit_test (enum machine_mode, int); static void do_jump_by_parts_greater (tree, int, rtx, rtx); static void do_jump_by_parts_equality (tree, rtx, rtx); static void do_compare_and_jump (tree, enum rtx_code, enum rtx_code, rtx, @@ -107,6 +109,45 @@ jumpif (tree exp, rtx label) do_jump (exp, NULL_RTX, label); } +/* Used internally by prefer_and_bit_test. */ + +static GTY(()) rtx and_reg; +static GTY(()) rtx and_test; +static GTY(()) rtx shift_test; + +/* Compare the relative costs of "(X & (1 << BITNUM))" and "(X >> BITNUM) & 1" + where X is an arbitrary register of mode MODE. Return true if the former + is preferred. */ + +static bool +prefer_and_bit_test (enum machine_mode mode, int bitnum) +{ + if (and_test == 0) + { + /* Set up rtxes for the two variations. Use NULL as a placeholder + for the BITNUM-based constants. */ + and_reg = gen_rtx_REG (mode, FIRST_PSEUDO_REGISTER); + and_test = gen_rtx_AND (mode, and_reg, NULL); + shift_test = gen_rtx_AND (mode, gen_rtx_ASHIFTRT (mode, and_reg, NULL), + const1_rtx); + } + else + { + /* Change the mode of the previously-created rtxes. */ + PUT_MODE (and_reg, mode); + PUT_MODE (and_test, mode); + PUT_MODE (shift_test, mode); + PUT_MODE (XEXP (shift_test, 0), mode); + } + + /* Fill in the integers. */ + XEXP (and_test, 1) = GEN_INT ((unsigned HOST_WIDE_INT) 1 << bitnum); + XEXP (XEXP (shift_test, 0), 1) = GEN_INT (bitnum); + + return (rtx_cost (and_test, IF_THEN_ELSE) + <= rtx_cost (shift_test, IF_THEN_ELSE)); +} + /* Generate code to evaluate EXP and jump to IF_FALSE_LABEL if the result is zero, or IF_TRUE_LABEL if the result is one. Either of IF_FALSE_LABEL and IF_TRUE_LABEL may be zero, @@ -212,6 +253,59 @@ do_jump (tree exp, rtx if_false_label, rtx if_true_label) break; case BIT_AND_EXPR: + /* fold_single_bit_test() converts (X & (1 << C)) into (X >> C) & 1. + See if the former is preferred for jump tests and restore it + if so. */ + if (integer_onep (TREE_OPERAND (exp, 1))) + { + tree exp0 = TREE_OPERAND (exp, 0); + rtx set_label, clr_label; + + /* Strip narrowing integral type conversions. */ + while ((TREE_CODE (exp0) == NOP_EXPR + || TREE_CODE (exp0) == CONVERT_EXPR + || TREE_CODE (exp0) == NON_LVALUE_EXPR) + && TREE_OPERAND (exp0, 0) != error_mark_node + && TYPE_PRECISION (TREE_TYPE (exp0)) + <= TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (exp0, 0)))) + exp0 = TREE_OPERAND (exp0, 0); + + /* "exp0 ^ 1" inverts the sense of the single bit test. */ + if (TREE_CODE (exp0) == BIT_XOR_EXPR + && integer_onep (TREE_OPERAND (exp0, 1))) + { + exp0 = TREE_OPERAND (exp0, 0); + clr_label = if_true_label; + set_label = if_false_label; + } + else + { + clr_label = if_false_label; + set_label = if_true_label; + } + + if (TREE_CODE (exp0) == RSHIFT_EXPR) + { + tree arg = TREE_OPERAND (exp0, 0); + tree shift = TREE_OPERAND (exp0, 1); + tree argtype = TREE_TYPE (arg); + if (TREE_CODE (shift) == INTEGER_CST + && compare_tree_int (shift, 0) >= 0 + && compare_tree_int (shift, HOST_BITS_PER_WIDE_INT) < 0 + && prefer_and_bit_test (TYPE_MODE (argtype), + TREE_INT_CST_LOW (shift))) + { + HOST_WIDE_INT mask = (HOST_WIDE_INT) 1 + << TREE_INT_CST_LOW (shift); + tree t = build_int_2 (mask, 0); + TREE_TYPE (t) = argtype; + do_jump (build (BIT_AND_EXPR, argtype, arg, t), + clr_label, set_label); + break; + } + } + } + /* If we are AND'ing with a small constant, do this comparison in the smallest type that fits. If the machine doesn't have comparisons that small, it will be converted back to the wider comparison. @@ -1003,3 +1097,5 @@ do_compare_and_jump (tree exp, enum rtx_code signed_code, ? expr_size (TREE_OPERAND (exp, 0)) : NULL_RTX), if_false_label, if_true_label); } + +#include "gt-dojump.h"