From a19eb9d236caf919b2a41445a72c30cffe12a432 Mon Sep 17 00:00:00 2001 From: Richard Guenther Date: Sun, 3 Jan 2010 12:06:02 +0000 Subject: [PATCH] re PR tree-optimization/42438 (Fix for PR38819 is too conservative) 2010-01-03 Richard Guenther PR tree-optimization/42438 * tree-ssa-pre.c (struct bb_bitmap_sets): Add contains_may_not_return_call flag. (BB_MAY_NOTRETURN): New. (valid_in_sets): Trapping nary operations are not valid in blocks that may not return. (insert_into_preds_of_block): Remove check for trapping expressions. (compute_avail): Compute also BB_MAY_NOTRETURN. * gcc.dg/tree-ssa/ssa-pre-27.c: New testcase. From-SVN: r155584 --- gcc/ChangeLog | 12 ++++++ gcc/testsuite/ChangeLog | 5 +++ gcc/testsuite/gcc.dg/tree-ssa/ssa-pre-27.c | 29 +++++++++++++++ gcc/tree-ssa-pre.c | 43 ++++++++++++++++------ 4 files changed, 78 insertions(+), 11 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/ssa-pre-27.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index c133aac3365..8065b245164 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,15 @@ +2010-01-03 Richard Guenther + + PR tree-optimization/42438 + * tree-ssa-pre.c (struct bb_bitmap_sets): Add + contains_may_not_return_call flag. + (BB_MAY_NOTRETURN): New. + (valid_in_sets): Trapping nary operations are not valid + in blocks that may not return. + (insert_into_preds_of_block): Remove check for trapping + expressions. + (compute_avail): Compute also BB_MAY_NOTRETURN. + 2010-01-03 Gerald Pfeifer * doc/invoke.texi: Add 2010 to copyright years. diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index d1580faf893..609589ca072 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2010-01-03 Richard Guenther + + PR tree-optimization/42438 + * gcc.dg/tree-ssa/ssa-pre-27.c: New testcase. + 2010-01-02 Richard Guenther PR testsuite/41651 diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-pre-27.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-pre-27.c new file mode 100644 index 00000000000..1d60a301320 --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-pre-27.c @@ -0,0 +1,29 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-pre" } */ + +int foo (int i, int j, int b) +{ + int res = 0; + if (b) + res = i/j; + /* We should insert the possibly trapping i/j. */ + res += i/j; + return res; +} + +extern void bar (void); +int foo2 (int i, int j, int b) +{ + int res = 0; + if (b) + res = i/j; + /* But we fail so here because of the possibly not returning + call in the same basic-block. */ + res += i/j; + bar (); + return res; +} + +/* { dg-final { scan-tree-dump-times "# prephitmp" 1 "pre" } } */ +/* { dg-final { scan-tree-dump-times "# prephitmp" 2 "pre" { xfail *-*-* } } } */ +/* { dg-final { cleanup-tree-dump "pre" } } */ diff --git a/gcc/tree-ssa-pre.c b/gcc/tree-ssa-pre.c index 52e973fadb6..7d9b9bf32d0 100644 --- a/gcc/tree-ssa-pre.c +++ b/gcc/tree-ssa-pre.c @@ -382,11 +382,14 @@ typedef struct bb_bitmap_sets bitmap expr_dies; /* True if we have visited this block during ANTIC calculation. */ - unsigned int visited:1; + unsigned int visited : 1; /* True we have deferred processing this block during ANTIC calculation until its successor is processed. */ unsigned int deferred : 1; + + /* True when the block contains a call that might not return. */ + unsigned int contains_may_not_return_call : 1; } *bb_value_sets_t; #define EXP_GEN(BB) ((bb_value_sets_t) ((BB)->aux))->exp_gen @@ -399,6 +402,7 @@ typedef struct bb_bitmap_sets #define EXPR_DIES(BB) ((bb_value_sets_t) ((BB)->aux))->expr_dies #define BB_VISITED(BB) ((bb_value_sets_t) ((BB)->aux))->visited #define BB_DEFERRED(BB) ((bb_value_sets_t) ((BB)->aux))->deferred +#define BB_MAY_NOTRETURN(BB) ((bb_value_sets_t) ((BB)->aux))->contains_may_not_return_call /* Basic block list in postorder. */ @@ -2032,6 +2036,13 @@ valid_in_sets (bitmap_set_t set1, bitmap_set_t set2, pre_expr expr, return false; } } + /* If the NARY may trap make sure the block does not contain + a possible exit point. + ??? This is overly conservative if we translate AVAIL_OUT + as the available expression might be after the exit point. */ + if (BB_MAY_NOTRETURN (block) + && vn_nary_may_trap (nary)) + return false; return true; } break; @@ -2469,6 +2480,7 @@ compute_antic (void) BB_VISITED (block) = 0; BB_DEFERRED (block) = 0; + /* While we are here, give empty ANTIC_IN sets to each block. */ ANTIC_IN (block) = bitmap_set_new (); PA_IN (block) = bitmap_set_new (); @@ -3187,16 +3199,6 @@ insert_into_preds_of_block (basic_block block, unsigned int exprnum, } } - /* Make sure we are not inserting trapping expressions. */ - FOR_EACH_EDGE (pred, ei, block->preds) - { - bprime = pred->src; - eprime = avail[bprime->index]; - if (eprime->kind == NARY - && vn_nary_may_trap (PRE_EXPR_NARY (eprime))) - return false; - } - /* Make the necessary insertions. */ FOR_EACH_EDGE (pred, ei, block->preds) { @@ -3804,6 +3806,8 @@ compute_avail (void) for (gsi = gsi_start_phis (block); !gsi_end_p (gsi); gsi_next (&gsi)) make_values_for_phi (gsi_stmt (gsi), block); + BB_MAY_NOTRETURN (block) = 0; + /* Now compute value numbers and populate value sets with all the expressions computed in BLOCK. */ for (gsi = gsi_start_bb (block); !gsi_end_p (gsi); gsi_next (&gsi)) @@ -3814,6 +3818,23 @@ compute_avail (void) stmt = gsi_stmt (gsi); gimple_set_uid (stmt, stmt_uid++); + /* Cache whether the basic-block has any non-visible side-effect + or control flow. + If this isn't a call or it is the last stmt in the + basic-block then the CFG represents things correctly. */ + if (is_gimple_call (stmt) + && !stmt_ends_bb_p (stmt)) + { + /* Non-looping const functions always return normally. + Otherwise the call might not return or have side-effects + that forbids hoisting possibly trapping expressions + before it. */ + int flags = gimple_call_flags (stmt); + if (!(flags & ECF_CONST) + || (flags & ECF_LOOPING_CONST_OR_PURE)) + BB_MAY_NOTRETURN (block) = 1; + } + FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_DEF) { pre_expr e = get_or_alloc_expr_for_name (op); -- 2.30.2