| Message ID | alpine.DEB.2.02.1303311510370.25614@stedding.saclay.inria.fr |
|---|---|
| State | New |
| Headers | show |
On Sun, Mar 31, 2013 at 6:31 AM, Marc Glisse <marc.glisse@inria.fr> wrote: > Hello, > > this adds constant folding of VEC_COND_EXPR at the tree level by forwarding > to the VEC_PERM_EXPR code (a merge is a special case of a permutation). The > CONSTRUCTOR case may be unreachable for now (it will probably need an extra > piece of code in tree-ssa-forwprop.c), but it seems better to add it at the > same time. > > bootstrap+testsuite on x86_64-linux-gnu. > > 2013-03-31 Marc Glisse <marc.glisse@inria.fr> > > PR tree-optimization/56790 > * fold-const.c (fold_ternary_loc) <VEC_COND_EXPR>: Add constant > folding. > > testsuite/ > * g++.dg/ext/pr56790-1.C: New testcase. > > -- > Marc Glisse > Index: gcc/testsuite/g++.dg/ext/pr56790-1.C > =================================================================== > --- gcc/testsuite/g++.dg/ext/pr56790-1.C (revision 0) > +++ gcc/testsuite/g++.dg/ext/pr56790-1.C (revision 0) > @@ -0,0 +1,16 @@ > +/* { dg-do compile } */ > +/* { dg-options "-O2 -fdump-tree-ccp1" } */ > + > +typedef long vec __attribute__ ((vector_size (2 * sizeof (long)))); > + > +vec f (void) > +{ > + vec a = { 5, 7 }; > + vec b = { 11, 13 }; > + vec m = { -1, 0 }; > + return m ? a : b; > +} > + > +/* { dg-final { scan-tree-dump "{ 5, 13 }" "ccp1" } } */ > +/* { dg-final { scan-tree-dump-not "VEC_COND_EXPR" "ccp1" } } */ > +/* { dg-final { cleanup-tree-dump "ccp1" } } */ > > Property changes on: gcc/testsuite/g++.dg/ext/pr56790-1.C > ___________________________________________________________________ > Added: svn:keywords > + Author Date Id Revision URL > Added: svn:eol-style > + native > > Index: gcc/fold-const.c > =================================================================== > --- gcc/fold-const.c (revision 197284) > +++ gcc/fold-const.c (working copy) > @@ -13917,20 +13917,43 @@ fold_ternary_loc (location_t loc, enum t > || VOID_TYPE_P (type))) > return pedantic_non_lvalue_loc (loc, tem); > return NULL_TREE; > } > else if (TREE_CODE (arg0) == VECTOR_CST) > { > if (integer_all_onesp (arg0)) > return pedantic_omit_one_operand_loc (loc, type, arg1, arg2); > if (integer_zerop (arg0)) > return pedantic_omit_one_operand_loc (loc, type, arg2, arg1); > + > + if ((TREE_CODE (arg1) == VECTOR_CST > + || TREE_CODE (arg1) == CONSTRUCTOR) > + && (TREE_CODE (arg2) == VECTOR_CST > + || TREE_CODE (arg2) == CONSTRUCTOR)) > + { > + unsigned int nelts = TYPE_VECTOR_SUBPARTS (type), i; > + unsigned char *sel = XALLOCAVEC (unsigned char, nelts); > + gcc_assert (nelts == VECTOR_CST_NELTS (arg0)); > + for (i = 0; i < nelts; i++) > + { > + tree val = VECTOR_CST_ELT (arg0, i); > + if (integer_all_onesp (val)) > + sel[i] = i; > + else if (integer_zerop (val)) > + sel[i] = nelts + i; > + else > + gcc_unreachable (); I think this gcc_unreachable here is incorrect as it could cause an internal compiler error for "target dependent code" Try for: typedef long vec __attribute__ ((vector_size (2 * sizeof (long)))); vec f (void) { vec a = { 5, 7 }; vec b = { 11, 13 }; vec m = { 3, 2 }; return m ? a : b; } I think for the above case we don't want to do any constant folding. Thanks, Andrew Pinski > + } > + tree t = fold_vec_perm (type, arg1, arg2, sel); > + if (t != NULL_TREE) > + return t; > + } > } > > if (operand_equal_p (arg1, op2, 0)) > return pedantic_omit_one_operand_loc (loc, type, arg1, arg0); > > /* If we have A op B ? A : C, we may be able to convert this to a > simpler expression, depending on the operation and the values > of B and C. Signed zeros prevent all of these transformations, > for reasons given above each one. > >
On Sun, 31 Mar 2013, Andrew Pinski wrote: > On Sun, Mar 31, 2013 at 6:31 AM, Marc Glisse <marc.glisse@inria.fr> wrote: >> Hello, >> >> this adds constant folding of VEC_COND_EXPR at the tree level by forwarding >> to the VEC_PERM_EXPR code (a merge is a special case of a permutation). The >> CONSTRUCTOR case may be unreachable for now (it will probably need an extra >> piece of code in tree-ssa-forwprop.c), but it seems better to add it at the >> same time. >> >> bootstrap+testsuite on x86_64-linux-gnu. >> >> 2013-03-31 Marc Glisse <marc.glisse@inria.fr> >> >> PR tree-optimization/56790 >> * fold-const.c (fold_ternary_loc) <VEC_COND_EXPR>: Add constant >> folding. >> >> testsuite/ >> * g++.dg/ext/pr56790-1.C: New testcase. >> >> -- >> Marc Glisse >> Index: gcc/testsuite/g++.dg/ext/pr56790-1.C >> =================================================================== >> --- gcc/testsuite/g++.dg/ext/pr56790-1.C (revision 0) >> +++ gcc/testsuite/g++.dg/ext/pr56790-1.C (revision 0) >> @@ -0,0 +1,16 @@ >> +/* { dg-do compile } */ >> +/* { dg-options "-O2 -fdump-tree-ccp1" } */ >> + >> +typedef long vec __attribute__ ((vector_size (2 * sizeof (long)))); >> + >> +vec f (void) >> +{ >> + vec a = { 5, 7 }; >> + vec b = { 11, 13 }; >> + vec m = { -1, 0 }; >> + return m ? a : b; >> +} >> + >> +/* { dg-final { scan-tree-dump "{ 5, 13 }" "ccp1" } } */ >> +/* { dg-final { scan-tree-dump-not "VEC_COND_EXPR" "ccp1" } } */ >> +/* { dg-final { cleanup-tree-dump "ccp1" } } */ >> >> Property changes on: gcc/testsuite/g++.dg/ext/pr56790-1.C >> ___________________________________________________________________ >> Added: svn:keywords >> + Author Date Id Revision URL >> Added: svn:eol-style >> + native >> >> Index: gcc/fold-const.c >> =================================================================== >> --- gcc/fold-const.c (revision 197284) >> +++ gcc/fold-const.c (working copy) >> @@ -13917,20 +13917,43 @@ fold_ternary_loc (location_t loc, enum t >> || VOID_TYPE_P (type))) >> return pedantic_non_lvalue_loc (loc, tem); >> return NULL_TREE; >> } >> else if (TREE_CODE (arg0) == VECTOR_CST) >> { >> if (integer_all_onesp (arg0)) >> return pedantic_omit_one_operand_loc (loc, type, arg1, arg2); >> if (integer_zerop (arg0)) >> return pedantic_omit_one_operand_loc (loc, type, arg2, arg1); >> + >> + if ((TREE_CODE (arg1) == VECTOR_CST >> + || TREE_CODE (arg1) == CONSTRUCTOR) >> + && (TREE_CODE (arg2) == VECTOR_CST >> + || TREE_CODE (arg2) == CONSTRUCTOR)) >> + { >> + unsigned int nelts = TYPE_VECTOR_SUBPARTS (type), i; >> + unsigned char *sel = XALLOCAVEC (unsigned char, nelts); >> + gcc_assert (nelts == VECTOR_CST_NELTS (arg0)); >> + for (i = 0; i < nelts; i++) >> + { >> + tree val = VECTOR_CST_ELT (arg0, i); >> + if (integer_all_onesp (val)) >> + sel[i] = i; >> + else if (integer_zerop (val)) >> + sel[i] = nelts + i; >> + else >> + gcc_unreachable (); > > I think this gcc_unreachable here is incorrect as it could cause an > internal compiler error for "target dependent code" > Try for: > typedef long vec __attribute__ ((vector_size (2 * sizeof (long)))); > > vec f (void) > { > vec a = { 5, 7 }; > vec b = { 11, 13 }; > vec m = { 3, 2 }; > return m ? a : b; > } > > I think for the above case we don't want to do any constant folding. For vectors, we decided in 4.8 that x ? y : z would mean vec_cond_expr <x != 0, y, z>, and that is what the C++ front-end generates, so your testcase works fine and returns a. Re-reading doc/generic.texi, I see: "If an element of the first operand evaluates to a zero value, the corresponding element of the result is taken from the third operand. If it evaluates to a minus one value, it is taken from the second operand. It should never evaluate to any other value currently, but optimizations should not rely on that property." Well, at least I am not silently relying on that property, but it looks like you are right and I am supposed to leave those (impossible) values alone.
On Sun, Mar 31, 2013 at 7:20 PM, Marc Glisse <marc.glisse@inria.fr> wrote: > On Sun, 31 Mar 2013, Andrew Pinski wrote: > >> On Sun, Mar 31, 2013 at 6:31 AM, Marc Glisse <marc.glisse@inria.fr> wrote: >>> >>> Hello, >>> >>> this adds constant folding of VEC_COND_EXPR at the tree level by >>> forwarding >>> to the VEC_PERM_EXPR code (a merge is a special case of a permutation). >>> The >>> CONSTRUCTOR case may be unreachable for now (it will probably need an >>> extra >>> piece of code in tree-ssa-forwprop.c), but it seems better to add it at >>> the >>> same time. >>> >>> bootstrap+testsuite on x86_64-linux-gnu. >>> >>> 2013-03-31 Marc Glisse <marc.glisse@inria.fr> >>> >>> PR tree-optimization/56790 >>> * fold-const.c (fold_ternary_loc) <VEC_COND_EXPR>: Add constant >>> folding. >>> >>> testsuite/ >>> * g++.dg/ext/pr56790-1.C: New testcase. >>> >>> -- >>> Marc Glisse >>> Index: gcc/testsuite/g++.dg/ext/pr56790-1.C >>> =================================================================== >>> --- gcc/testsuite/g++.dg/ext/pr56790-1.C (revision 0) >>> +++ gcc/testsuite/g++.dg/ext/pr56790-1.C (revision 0) >>> @@ -0,0 +1,16 @@ >>> +/* { dg-do compile } */ >>> +/* { dg-options "-O2 -fdump-tree-ccp1" } */ >>> + >>> +typedef long vec __attribute__ ((vector_size (2 * sizeof (long)))); >>> + >>> +vec f (void) >>> +{ >>> + vec a = { 5, 7 }; >>> + vec b = { 11, 13 }; >>> + vec m = { -1, 0 }; >>> + return m ? a : b; >>> +} >>> + >>> +/* { dg-final { scan-tree-dump "{ 5, 13 }" "ccp1" } } */ >>> +/* { dg-final { scan-tree-dump-not "VEC_COND_EXPR" "ccp1" } } */ >>> +/* { dg-final { cleanup-tree-dump "ccp1" } } */ >>> >>> Property changes on: gcc/testsuite/g++.dg/ext/pr56790-1.C >>> ___________________________________________________________________ >>> Added: svn:keywords >>> + Author Date Id Revision URL >>> Added: svn:eol-style >>> + native >>> >>> Index: gcc/fold-const.c >>> =================================================================== >>> --- gcc/fold-const.c (revision 197284) >>> +++ gcc/fold-const.c (working copy) >>> @@ -13917,20 +13917,43 @@ fold_ternary_loc (location_t loc, enum t >>> || VOID_TYPE_P (type))) >>> return pedantic_non_lvalue_loc (loc, tem); >>> return NULL_TREE; >>> } >>> else if (TREE_CODE (arg0) == VECTOR_CST) >>> { >>> if (integer_all_onesp (arg0)) >>> return pedantic_omit_one_operand_loc (loc, type, arg1, arg2); >>> if (integer_zerop (arg0)) >>> return pedantic_omit_one_operand_loc (loc, type, arg2, arg1); >>> + >>> + if ((TREE_CODE (arg1) == VECTOR_CST >>> + || TREE_CODE (arg1) == CONSTRUCTOR) >>> + && (TREE_CODE (arg2) == VECTOR_CST >>> + || TREE_CODE (arg2) == CONSTRUCTOR)) >>> + { >>> + unsigned int nelts = TYPE_VECTOR_SUBPARTS (type), i; >>> + unsigned char *sel = XALLOCAVEC (unsigned char, nelts); >>> + gcc_assert (nelts == VECTOR_CST_NELTS (arg0)); >>> + for (i = 0; i < nelts; i++) >>> + { >>> + tree val = VECTOR_CST_ELT (arg0, i); >>> + if (integer_all_onesp (val)) >>> + sel[i] = i; >>> + else if (integer_zerop (val)) >>> + sel[i] = nelts + i; >>> + else >>> + gcc_unreachable (); >> >> >> I think this gcc_unreachable here is incorrect as it could cause an >> internal compiler error for "target dependent code" >> Try for: >> typedef long vec __attribute__ ((vector_size (2 * sizeof (long)))); >> >> vec f (void) >> { >> vec a = { 5, 7 }; >> vec b = { 11, 13 }; >> vec m = { 3, 2 }; >> return m ? a : b; >> } >> >> I think for the above case we don't want to do any constant folding. > > > For vectors, we decided in 4.8 that x ? y : z would mean vec_cond_expr <x != > 0, y, z>, and that is what the C++ front-end generates, so your testcase > works fine and returns a. > > Re-reading doc/generic.texi, I see: > > "If an element of the first operand evaluates to a zero value, the > corresponding element of the result is taken from the third operand. If it > evaluates to a minus one value, it is taken from the second operand. It > should never evaluate to any other value currently, but optimizations should > not rely on that property." > > Well, at least I am not silently relying on that property, but it looks like > you are right and I am supposed to leave those (impossible) values alone. Yes, in general just don't fold if you hit unexpected things (return NULL_TREE). Ok with that change. Thanks, Richard. > -- > Marc Glisse >
Index: gcc/testsuite/g++.dg/ext/pr56790-1.C =================================================================== --- gcc/testsuite/g++.dg/ext/pr56790-1.C (revision 0) +++ gcc/testsuite/g++.dg/ext/pr56790-1.C (revision 0) @@ -0,0 +1,16 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-ccp1" } */ + +typedef long vec __attribute__ ((vector_size (2 * sizeof (long)))); + +vec f (void) +{ + vec a = { 5, 7 }; + vec b = { 11, 13 }; + vec m = { -1, 0 }; + return m ? a : b; +} + +/* { dg-final { scan-tree-dump "{ 5, 13 }" "ccp1" } } */ +/* { dg-final { scan-tree-dump-not "VEC_COND_EXPR" "ccp1" } } */ +/* { dg-final { cleanup-tree-dump "ccp1" } } */ Property changes on: gcc/testsuite/g++.dg/ext/pr56790-1.C ___________________________________________________________________ Added: svn:keywords + Author Date Id Revision URL Added: svn:eol-style + native Index: gcc/fold-const.c =================================================================== --- gcc/fold-const.c (revision 197284) +++ gcc/fold-const.c (working copy) @@ -13917,20 +13917,43 @@ fold_ternary_loc (location_t loc, enum t || VOID_TYPE_P (type))) return pedantic_non_lvalue_loc (loc, tem); return NULL_TREE; } else if (TREE_CODE (arg0) == VECTOR_CST) { if (integer_all_onesp (arg0)) return pedantic_omit_one_operand_loc (loc, type, arg1, arg2); if (integer_zerop (arg0)) return pedantic_omit_one_operand_loc (loc, type, arg2, arg1); + + if ((TREE_CODE (arg1) == VECTOR_CST + || TREE_CODE (arg1) == CONSTRUCTOR) + && (TREE_CODE (arg2) == VECTOR_CST + || TREE_CODE (arg2) == CONSTRUCTOR)) + { + unsigned int nelts = TYPE_VECTOR_SUBPARTS (type), i; + unsigned char *sel = XALLOCAVEC (unsigned char, nelts); + gcc_assert (nelts == VECTOR_CST_NELTS (arg0)); + for (i = 0; i < nelts; i++) + { + tree val = VECTOR_CST_ELT (arg0, i); + if (integer_all_onesp (val)) + sel[i] = i; + else if (integer_zerop (val)) + sel[i] = nelts + i; + else + gcc_unreachable (); + } + tree t = fold_vec_perm (type, arg1, arg2, sel); + if (t != NULL_TREE) + return t; + } } if (operand_equal_p (arg1, op2, 0)) return pedantic_omit_one_operand_loc (loc, type, arg1, arg0); /* If we have A op B ? A : C, we may be able to convert this to a simpler expression, depending on the operation and the values of B and C. Signed zeros prevent all of these transformations, for reasons given above each one.