On Wed, Nov 18, 2015 at 09:36:21AM +0100, Richard Biener wrote: > On Wed, 18 Nov 2015, Senthil Kumar Selvaraj wrote: > > > On Mon, Nov 16, 2015 at 10:02:15AM +0100, Richard Biener wrote: > > > On Sat, 14 Nov 2015, Senthil Kumar Selvaraj wrote: > > > > > > > On Sat, Nov 14, 2015 at 09:57:40AM +0100, Richard Biener wrote: > > > > > On November 14, 2015 9:49:28 AM GMT+01:00, Senthil Kumar Selvaraj > > > > > <senthil_kumar.selva...@atmel.com> wrote: > > > > > >On Sat, Nov 14, 2015 at 09:13:41AM +0100, Marc Glisse wrote: > > > > > >> On Sat, 14 Nov 2015, Senthil Kumar Selvaraj wrote: > > > > > >> > > > > > >> >This patch came out of a discussion held in the gcc mailing list > > > > > >> >(https://gcc.gnu.org/ml/gcc/2015-11/msg00067.html). > > > > > >> > > > > > > >> >The patch restricts folding of conditional exprs with lhs > > > > > >> >previously > > > > > >> >set by a type conversion to occur only if the source of the type > > > > > >> >conversion's mode is word mode or smaller. > > > > > >> > > > > > > >> >Bootstrapped and reg tested on x86_64 (with > > > > > >--enable-languages=c,c++). > > > > > >> > > > > > > >> >If ok, could you commit please? I don't have commit access. > > > > > >> > > > > > > >> >Regards > > > > > >> >Senthil > > > > > >> > > > > > > >> >gcc/ChangeLog > > > > > >> > > > > > > >> >2015-11-11 Senthil Kumar Selvaraj > > > > > ><senthil_kumar.selva...@atmel.com> > > > > > >> > > > > > > >> > * tree-vrp.c (simplify_cond_using_ranges): Fold only > > > > > >> > if innerop's mode is word_mode or smaller. > > > > > >> > > > > > > >> > > > > > > >> >diff --git gcc/tree-vrp.c gcc/tree-vrp.c > > > > > >> >index e2393e4..c139bc6 100644 > > > > > >> >--- gcc/tree-vrp.c > > > > > >> >+++ gcc/tree-vrp.c > > > > > >> >@@ -9467,6 +9467,8 @@ simplify_cond_using_ranges (gcond *stmt) > > > > > >> > innerop = gimple_assign_rhs1 (def_stmt); > > > > > >> > > > > > > >> > if (TREE_CODE (innerop) == SSA_NAME > > > > > >> >+ && (GET_MODE_SIZE(TYPE_MODE(TREE_TYPE(innerop))) > > > > > >> >+ <= GET_MODE_SIZE(word_mode)) > > > > > >> > && !POINTER_TYPE_P (TREE_TYPE (innerop))) > > > > > >> > { > > > > > >> > value_range *vr = get_value_range (innerop); > > > > > >> > > > > > >> I thought the result of the discussion was that the transformation > > > > > >> is > > > > > >ok if > > > > > >> either it is narrowing or it widens but to something no bigger than > > > > > >> word_mode. So you should have 2 comparisons, or 1 with a max. > > > > > > > > > > > >Hmm, I came to the opposite conclusion - I thought Richard only > > > > > >okayed > > > > > >"widening upto word-mode", not the narrowing. > > > > > > > > > > I didn't mean to suggest narrowing is not OK. In fact narrowing is > > > > > always OK. > > > > > > > > My bad. Here's a revised patch that checks for both conditions, using > > > > max as Marc suggested to limit to word_mode or narrowing conversions. > > > > > > > > Bootstrapped and regtested for x86_64 with c and c++. > > > > > > > > Is this ok? If yes, would you commit it > > > > for me please? I don't have commit access. > > > > > > > > gcc/ChangeLog > > > > 2015-11-14 Senthil Kumar Selvaraj <senthil_kumar.selva...@atmel.com> > > > > > > > > * tree-vrp.c (simplify_cond_using_ranges): Fold only > > > > if innerop's mode smaller or equal to word_mode or op0's mode. > > > > > > > > > > > > diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c > > > > index e2393e4..cfd90e7 100644 > > > > --- a/gcc/tree-vrp.c > > > > +++ b/gcc/tree-vrp.c > > > > @@ -9467,7 +9467,10 @@ simplify_cond_using_ranges (gcond *stmt) > > > > innerop = gimple_assign_rhs1 (def_stmt); > > > > > > > > if (TREE_CODE (innerop) == SSA_NAME > > > > - && !POINTER_TYPE_P (TREE_TYPE (innerop))) > > > > + && !POINTER_TYPE_P (TREE_TYPE (innerop)) > > > > + && (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (innerop))) > > > > + <= std::max (GET_MODE_SIZE (word_mode), > > > > + GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (op0)))))) > > > > > > Please use TYPE_PRECISION (...) and GET_MODE_PRECISION (word_mode) and > > > add a comment as to what we are testing here and why. > > > > > > Btw, ideally we'd factor out a > > > > > > bool > > > desired_pro_or_demotion_p (tree to_type, tree from_type) {} > > > > > > function somewhere as we have similar tests throughout the compiler > > > that we might want to unify (and also have a central place to > > > eventually add a target hook if ever desired). > > > > > > In fact in other places we also check that the type we promote/demote > > > to matches its mode precision or the type we promote/demote from > > > already does not. > > > > > > I'd suggest tree.[ch] for that function. > > > > > > Please also add a testcase. > > > > How does the below patch look? Bootstrapped, but not regtested yet. > > > > The testcase was rather tricky to write - I wasn't sure how to reliably > > get a type bigger than a word for all targets. I resorted to __int128, > > not sure it's a good idea though - I should probably add dg-skip-if for > > targets that don't support that. Do you know of a better way to write > > that? > > Ah, I was hoping for an avr specific testcase (as you have that already) > scanning assembler output - after all we want to check the final result, > not just what VRP did. > > > diff --git gcc/tree-vrp.c gcc/tree-vrp.c > > index 5d085b4..4513b88 100644 > > --- gcc/tree-vrp.c > > +++ gcc/tree-vrp.c > > @@ -9467,7 +9467,8 @@ simplify_cond_using_ranges (gcond *stmt) > > innerop = gimple_assign_rhs1 (def_stmt); > > > > if (TREE_CODE (innerop) == SSA_NAME > > - && !POINTER_TYPE_P (TREE_TYPE (innerop))) > > + && !POINTER_TYPE_P (TREE_TYPE (innerop)) > > + && desired_pro_or_demotion_p (innerop, op0)) > > { > > value_range *vr = get_value_range (innerop); > > > > diff --git gcc/tree.h gcc/tree.h > > index 0b9c3b9..91099ed 100644 > > --- gcc/tree.h > > +++ gcc/tree.h > > @@ -5316,4 +5316,18 @@ get_decl_source_range (tree decl) > > return get_range_from_loc (line_table, loc); > > } > > > > +/* Return true if it makes sense to promote/demote from_type to to_type. */ > > +inline bool > > +desired_pro_or_demotion_p (tree to_type, tree from_type) > > Please pass in a type here. > > Otherwise ok.
See modified patch below. If you think vrp98.c is unnecessary, feel free to dump it :). If ok, could you commit it for me please? I don't have commit access. Regards Senthil gcc/ChangeLog 2015-11-19 Senthil Kumar Selvaraj <senthil_kumar.selva...@atmel.com> * tree.h (desired_pro_or_demotion_p): New function. * tree-vrp.c (simplify_cond_using_ranges): Call it. gcc/testsuite/ChangeLog 2015-11-19 Senthil Kumar Selvaraj <senthil_kumar.selva...@atmel.com> * gcc.dg/tree-ssa/vrp98.c: New testcase. * gcc.target/avr/uint8-single-reg.c: New testcase. diff --git gcc/testsuite/gcc.dg/tree-ssa/vrp98.c gcc/testsuite/gcc.dg/tree-ssa/vrp98.c new file mode 100644 index 0000000..982f091 --- /dev/null +++ gcc/testsuite/gcc.dg/tree-ssa/vrp98.c @@ -0,0 +1,41 @@ +/* { dg-do compile } */ +/* { dg-require-effective-target int128 } */ +/* { dg-options "-Os -fdump-tree-vrp1-details" } */ + +#include <stdint.h> +#include <limits.h> + +typedef unsigned int word __attribute__((mode(word))); +typedef unsigned __int128 bigger_than_word; + +int +foo (bigger_than_word a, word b, uint8_t c) +{ + /* Must fold use of t1 into use of b, as b is no wider than word_mode. */ + const uint8_t t1 = b % UCHAR_MAX; + + /* Must NOT fold use of t2 into use of a, as a is wider than word_mode. */ + const uint8_t t2 = a % UCHAR_MAX; + + /* Must fold use of t3 into use of c, as c is narrower than t3. */ + const uint32_t t3 = (const uint32_t)(c >> 1); + + uint16_t ret = 0; + + if (t1 == 1) + ret = 20; + else if (t2 == 2) + ret = 30; + else if (t3 == 3) + ret = 40; + /* Th extra condition below is necessary to prevent a prior pass from + folding away the cast. Ignored in scan-tree-dump. */ + else if (t3 == 4) + ret = 50; + + return ret; +} + +/* { dg-final { scan-tree-dump "Folded into: if \\(_\[0-9\]+ == 1\\)" "vrp1" } } */ +/* { dg-final { scan-tree-dump-not "Folded into: if \\(_\[0-9\]+ == 2\\)" "vrp1" } } */ +/* { dg-final { scan-tree-dump "Folded into: if \\(_\[0-9\]+ == 3\\)" "vrp1" } } */ diff --git gcc/testsuite/gcc.target/avr/uint8-single-reg.c gcc/testsuite/gcc.target/avr/uint8-single-reg.c new file mode 100644 index 0000000..291b56c --- /dev/null +++ gcc/testsuite/gcc.target/avr/uint8-single-reg.c @@ -0,0 +1,24 @@ +/* { dg-do compile } */ +/* { dg-options "-Os" } */ + +/* This testcase verifies that a uint8_t variable assigned from a wider variable + with the same range is held in a single register. VRP must not fold away the + conversion and use two regs to hold the uint16_t - widenings are ok only upto + word mode (1 byte for AVR). +*/ + +unsigned int foo(const unsigned int wvalue) +{ + const unsigned char type = (wvalue >> 8); + unsigned int size = 0; + + if (type == 1) + { + size = 20; + } + return size; +} + +/* { dg-final { scan-assembler "cpi r25,lo8\\(1\\)" } } */ +/* { dg-final { scan-assembler-not "cpc r\\d+,__zero_reg__" } } */ + diff --git gcc/tree-vrp.c gcc/tree-vrp.c index e67048e..6a4ff30 100644 --- gcc/tree-vrp.c +++ gcc/tree-vrp.c @@ -9459,7 +9459,8 @@ simplify_cond_using_ranges (gcond *stmt) innerop = gimple_assign_rhs1 (def_stmt); if (TREE_CODE (innerop) == SSA_NAME - && !POINTER_TYPE_P (TREE_TYPE (innerop))) + && !POINTER_TYPE_P (TREE_TYPE (innerop)) + && desired_pro_or_demotion_p (TREE_TYPE (innerop), TREE_TYPE (op0))) { value_range *vr = get_value_range (innerop); diff --git gcc/tree.h gcc/tree.h index 41c0f7c..cb52deb 100644 --- gcc/tree.h +++ gcc/tree.h @@ -5358,4 +5358,18 @@ get_decl_source_range (tree decl) return get_range_from_loc (line_table, loc); } +/* Return true if it makes sense to promote/demote from_type to to_type. */ +inline bool +desired_pro_or_demotion_p (const_tree to_type, const_tree from_type) +{ + unsigned int to_type_precision = TYPE_PRECISION (to_type); + + /* OK to promote if to_type is no bigger than word_mode. */ + if (to_type_precision <= GET_MODE_PRECISION (word_mode)) + return true; + + /* Otherwise, allow only if narrowing or same precision conversions. */ + return to_type_precision <= TYPE_PRECISION (from_type); +} + #endif /* GCC_TREE_H */