Submitter | Kai Tietz |
---|---|

Date | May 11, 2011, 9 a.m. |

Message ID | <BANLkTinuQk-K4GKv6hpwJ2o=ZxYxO-68sA@mail.gmail.com> |

Download | mbox | patch |

Permalink | /patch/95204/ |

State | New |

Headers | show |

## Comments

On Wed, May 11, 2011 at 11:00 AM, Kai Tietz <ktietz70@googlemail.com> wrote: > Hi, > > By investigating the conditional expression handling I found some > causes, why TRUTH operations AND, ANDIF, OR, XOR, and ORIF are > appearing withing conditional folding during gimplification. > The reason for this can be that the truth expression is simply used as > result of an assignment or return statement, which then leads to the > issue that expression has lhs type. By this reason it is still > necessary to have in TRUTH operations type-cast after boolifying it > for later operation, if type isn't of kind boolean. Therefore it is > necessary for conditional to check if their arms might be TRUTH > results and therefore doing boolification of the arms, too. You are not making much sense - gimple_boolify already boolifies both arms. It assumes that if the expr is bool already the arms are as well - I'm not sure that always holds, so defering that check as your patch did probably makes sense. Richard. > 2011-05-11 Kai Tietz > > * gimplify.c (gimple_boolify): Handle COND_EXPR > and make sure that even if type is BOOLEAN for > TRUTH-opcodes the operands getting boolified. > (gimple_has_cond_boolean_arms): Helper function to > detect if condition is a TRUTH operation in arms. > (gimple_is_truth_op): Checks if operand is of BOOLEAN > kind. > (gimplify_expr): Boolify operand condition for > COND_EXPR and try to see if condition might be an TRUTH operation. > Boolify truth opcodes AND, ANDIF, OR, ORIF, and XOR. Additional > take care that we keep expression's type. > > Tested on x86_64-w64-mingw32 and x86_64-pc-linux-gnu. Ok for apply? > > Regards, > Kai >

2011/5/11 Richard Guenther <richard.guenther@gmail.com>: > On Wed, May 11, 2011 at 11:00 AM, Kai Tietz <ktietz70@googlemail.com> wrote: >> Hi, >> >> By investigating the conditional expression handling I found some >> causes, why TRUTH operations AND, ANDIF, OR, XOR, and ORIF are >> appearing withing conditional folding during gimplification. >> The reason for this can be that the truth expression is simply used as >> result of an assignment or return statement, which then leads to the >> issue that expression has lhs type. By this reason it is still >> necessary to have in TRUTH operations type-cast after boolifying it >> for later operation, if type isn't of kind boolean. Therefore it is >> necessary for conditional to check if their arms might be TRUTH >> results and therefore doing boolification of the arms, too. > > You are not making much sense - gimple_boolify already boolifies > both arms. It assumes that if the expr is bool already the arms are > as well - I'm not sure that always holds, so defering that check as > your patch did probably makes sense. It makes absolutely sense. Simply try the following example: int foo (int a, int b, int c) { int e = (a && b); return e ? (c && !a) : (c && a && b); } You will see that by this you have TRUTH AND operations with none boolean type, due the fact that for a conditional only the cond part was converted. This patch checks that inner arms getting boolified, if result of condition on both arms is a TRUTH result. Regards, Kai

For more detail what happens and why this conditional handling is necessary: The sample code is: int foo (int a, int b) { return (a ? b != 3 : 0); } leads for variant without condition boolifying of arms to: ;; Function foo (foo) foo (int a, int b) { int D.1991; int D.1990; int D.1989; <bb 2>: D.1990_2 = a_1(D) != 0; D.1991_4 = b_3(D) != 3; D.1989_5 = D.1991_4 & D.1990_2; return D.1989_5; } with this code we see ;; Function foo (foo) foo (int a, int b) { _Bool D.1992; _Bool D.1991; _Bool D.1990; int D.1989; <bb 2>: D.1990_2 = a_1(D) != 0; D.1991_4 = b_3(D) != 3; D.1992_5 = D.1991_4 & D.1990_2; D.1989_6 = (int) D.1992_5; return D.1989_6; } So you see that by this, the SSA variable having _Bool type, as to be wished, and not being handled as int. Regards, Kai

## Patch

Index: gcc/gcc/gimplify.c =================================================================== --- gcc.orig/gcc/gimplify.c 2011-05-10 18:31:40.000000000 +0200 +++ gcc/gcc/gimplify.c 2011-05-11 10:20:30.413964700 +0200 @@ -102,6 +102,7 @@ typedef struct gimple_temp_hash_elt /* Forward declaration. */ static enum gimplify_status gimplify_compound_expr (tree *, gimple_seq *, bool); +static bool gimple_has_cond_boolean_arms (tree); /* Mark X addressable. Unlike the langhook we expect X to be in gimple form and we don't do any syntax checking. */ @@ -2824,11 +2825,26 @@ gimple_boolify (tree expr) } } - if (TREE_CODE (type) == BOOLEAN_TYPE) - return expr; - switch (TREE_CODE (expr)) { + case COND_EXPR: + /* If we have a conditional expression, which shall be + boolean, take care we boolify also their left and right arm. */ + if (TREE_OPERAND (expr, 2) != NULL_TREE && !VOID_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 2)))) + TREE_OPERAND (expr, 2) = gimple_boolify (TREE_OPERAND (expr, 2)); + if (TREE_OPERAND (expr, 1) != NULL_TREE && !VOID_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 1)))) + TREE_OPERAND (expr, 1) = gimple_boolify (TREE_OPERAND (expr, 1)); + TREE_OPERAND (expr, 0) = gimple_boolify (TREE_OPERAND (expr, 0)); + if (TREE_CODE (type) == BOOLEAN_TYPE) + return expr; + if (!VOID_TYPE_P (TREE_TYPE (expr))) + { + /* These expressions always produce boolean results. */ + TREE_TYPE (expr) = boolean_type_node; + } + else + return fold_convert_loc (loc, boolean_type_node, expr); + case TRUTH_AND_EXPR: case TRUTH_OR_EXPR: case TRUTH_XOR_EXPR: @@ -2851,6 +2867,8 @@ gimple_boolify (tree expr) default: /* Other expressions that get here must have boolean values, but might need to be converted to the appropriate mode. */ + if (TREE_CODE (type) == BOOLEAN_TYPE) + return expr; return fold_convert_loc (loc, boolean_type_node, expr); } } @@ -2909,6 +2927,66 @@ generic_expr_could_trap_p (tree expr) return false; } +/* This function checks if OP is of TRUTH kind expression. It special-case + COND_EXPR, as here we need to look on results, too. See function + gimple_has_cond_boolean_arms () for more details. + If OP is of possible kind TRUTH expression, TRUE is returned, + otherwise FALSE is returned. + This functions assumes that all TRUTH operations, COND_EXPR with + boolean arms, INTEGER_CST with value of one or zero, and any + comparision has boolean result. */ + +static bool +gimple_is_truth_op (tree op) +{ + if (VOID_TYPE_P (TREE_TYPE (op))) + return false; + if (TREE_CODE (TREE_TYPE (op)) == BOOLEAN_TYPE) + return true; + switch (TREE_CODE (op)) + { + case TRUTH_AND_EXPR: + case TRUTH_OR_EXPR: + case TRUTH_XOR_EXPR: + case TRUTH_ANDIF_EXPR: + case TRUTH_ORIF_EXPR: + case TRUTH_NOT_EXPR: + return true; + case COND_EXPR: + return gimple_has_cond_boolean_arms (op); + case INTEGER_CST: + if (integer_zerop (op) || integer_onep (op)) + return true; + return false; + default: + if (TREE_CODE_CLASS (TREE_CODE (op)) == tcc_comparison) + return true; + break; + } + return false; +} + +/* This function checks if all arms of the condition expression EXPR + are of kind TRUTH. If so, it returns TRUE, otherwise FALSE. */ + +static bool +gimple_has_cond_boolean_arms (tree expr) +{ + tree type = TREE_TYPE (expr); + tree arm1 = TREE_OPERAND (expr, 0); + tree arm2 = TREE_OPERAND (expr, 1); + + if (VOID_TYPE_P (type)) + return false; + if (!arm1 && !arm2) + return false; + if (arm1 && !gimple_is_truth_op (arm1)) + return false; + if (arm2 && !gimple_is_truth_op (arm2)) + return false; + return true; +} + /* Convert the conditional expression pointed to by EXPR_P '(p) ? a : b;' into @@ -6714,7 +6792,25 @@ gimplify_expr (tree *expr_p, gimple_seq break; case COND_EXPR: - ret = gimplify_cond_expr (expr_p, pre_p, fallback); + { + tree type = TREE_TYPE (*expr_p); + tree nexpr = NULL_TREE; + if (TREE_CODE (type) == BOOLEAN_TYPE + || !gimple_has_cond_boolean_arms (*expr_p)) + type = NULL; + if (type) + nexpr = gimple_boolify (*expr_p); + + TREE_OPERAND (*expr_p, 0) = gimple_boolify (TREE_OPERAND (*expr_p, 0)); + + ret = gimplify_cond_expr (expr_p, pre_p, fallback); + + if (nexpr) + { + *expr_p = fold_convert (type, *expr_p); + ret = GS_OK; + } + } /* C99 code may assign to an array in a structure value of a conditional expression, and this has undefined behavior @@ -6762,6 +6858,18 @@ gimplify_expr (tree *expr_p, gimple_seq case TRUTH_ANDIF_EXPR: case TRUTH_ORIF_EXPR: + /* This shouldn't happen, but due fold-const (and here especially + fold_truth_not_expr) happily uses operand type and doesn't + automatically uses boolean_type as result, this happens. */ + if (TREE_CODE (TREE_TYPE (*expr_p)) != BOOLEAN_TYPE) + { + tree type = TREE_TYPE (*expr_p); + + *expr_p = fold_convert (type, gimple_boolify (*expr_p)); + ret = GS_OK; + break; + } + *expr_p = gimple_boolify (*expr_p); /* Pass the source location of the outer expression. */ ret = gimplify_boolean_expr (expr_p, saved_location); break; @@ -7203,6 +7311,17 @@ gimplify_expr (tree *expr_p, gimple_seq case TRUTH_AND_EXPR: case TRUTH_OR_EXPR: case TRUTH_XOR_EXPR: + /* This shouldn't happen, but due fold-const (and here especially + fold_truth_not_expr) happily uses operand type and doesn't + automatically uses boolean_type as result, this happens. */ + if (TREE_CODE (TREE_TYPE (*expr_p)) != BOOLEAN_TYPE) + { + tree type = TREE_TYPE (*expr_p); + *expr_p = fold_convert (type, gimple_boolify (*expr_p)); + ret = GS_OK; + break; + } + *expr_p = gimple_boolify (*expr_p); /* Classified as tcc_expression. */ goto expr_2;