On Wed, May 21, 2014 at 9:45 PM, Eric Botcazou <ebotca...@adacore.com> wrote: > Hi, > > one of the transformations performed by associate_plusminus is: > > /* Second match patterns that allow contracting a plus-minus pair > irrespective of overflow issues. > > [...] > (T)(P + A) - (T)P -> (T)A > > but it is actually applied only to POINTER_PLUS_EXPR and pointer types: > > /* (T)(ptr + adj) - (T)ptr -> (T)adj. */ > > It turns out that this pattern arises for size computations of array slices in > Ada, which are done in integer types; for the attached testcase, extending the > transformation to integer types makes it possible to eliminate a call to the > alloca builtin. > > Tested on x86_64-suse-linux, OK for the mainline?
I'm a little worried that introducing PLUS_EXPR_CODE_P and friends invites too easy (not well thought) uses of it - they are distinct enough that we have very few "common" code-paths given the constraints on op2 of POINTER_PLUS_EXPR. Thus I'd say ok without adding those. Thanks, Richard. > 2014-05-21 Eric Botcazou <ebotca...@adacore.com> > > * tree.h (PLUS_EXPR_CODE_P): New macro. > (PLUS_EXPR_P): Likewise. > (CASE_PLUS): Likewise. > * tree-ssa-forwprop.c (associate_plusminus): Extend (T)(P+A) - (T)P > -> (T)A transformation to integer types. > > > 2014-05-21 Eric Botcazou <ebotca...@adacore.com> > > * gnat.dg/opt37.ad[sb]: New test. > > > -- > Eric Botcazou
