From 31a52b868a209f0c8f3ade10a91148664526dc9b Mon Sep 17 00:00:00 2001 From: Roger Sayle Date: Wed, 19 May 2004 13:54:15 +0000 Subject: [PATCH] tm.texi (TARGET_RTX_COSTS): Document that instruction costs should be based on code size when... * doc/tm.texi (TARGET_RTX_COSTS): Document that instruction costs should be based on code size when optimizing for size. From-SVN: r82025 --- gcc/ChangeLog | 5 +++++ gcc/doc/tm.texi | 8 +++++++- 2 files changed, 12 insertions(+), 1 deletion(-) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 3b616152160..ca2069d13fa 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2004-05-19 Roger Sayle + + * doc/tm.texi (TARGET_RTX_COSTS): Document that instruction + costs should be based on code size when optimizing for size. + 2004-05-19 Paolo Bonzini * fold-const.c: Remove non-printable character 160. diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi index 43543a81103..67f4b7608a4 100644 --- a/gcc/doc/tm.texi +++ b/gcc/doc/tm.texi @@ -5456,7 +5456,13 @@ instructions. On entry to the hook, @code{*@var{total}} contains a default estimate for the cost of the expression. The hook should modify this value as -necessary. +necessary. Traditionally, the default costs are @code{COSTS_N_INSNS (5)} +for multiplications, @code{COSTS_N_INSNS (7)} for division and modulus +operations, and @code{COSTS_N_INSNS (1)} for all other operations. + +When optimizing for code size, i.e@. when @code{optimize_size} is +non-zero, this target hook should be used to estimate the relative +size cost of an expression, again relative to @code{COSTS_N_INSNS}. The hook returns true when all subexpressions of @var{x} have been processed, and false when @code{rtx_cost} should recurse. -- 2.30.2