While looking at differences between what minmax_replacement
and match_simplify_replacement does. I noticed that they sometimes
chose different edges to remove. I decided we should be able to do
better and be able to remove both empty basic blocks in the
case of match_simplify_replacement as that moves the statements.
This also updates the testcases as now match_simplify_replacement
will remove the unused MIN/MAX_EXPR and they were checking for
those.
OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.
gcc/ChangeLog:
* tree-ssa-phiopt.cc (copy_phi_args): New function.
(replace_phi_edge_with_variable): Handle diamond form bb
with forwarder only empty blocks better.
gcc/testsuite/ChangeLog:
* gcc.dg/tree-ssa/minmax-15.c: Update test.
* gcc.dg/tree-ssa/minmax-16.c: Update test.
* gcc.dg/tree-ssa/minmax-3.c: Update test.
* gcc.dg/tree-ssa/minmax-4.c: Update test.
* gcc.dg/tree-ssa/minmax-5.c: Update test.
* gcc.dg/tree-ssa/minmax-8.c: Update test.
---
gcc/testsuite/gcc.dg/tree-ssa/minmax-15.c | 3 +-
gcc/testsuite/gcc.dg/tree-ssa/minmax-16.c | 9 ++--
gcc/testsuite/gcc.dg/tree-ssa/minmax-3.c | 2 +-
gcc/testsuite/gcc.dg/tree-ssa/minmax-4.c | 2 +-
gcc/testsuite/gcc.dg/tree-ssa/minmax-5.c | 2 +-
gcc/testsuite/gcc.dg/tree-ssa/minmax-8.c | 2 +-
gcc/tree-ssa-phiopt.cc | 51 ++++++++++++++++++++++-
7 files changed, 59 insertions(+), 12 deletions(-)
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/minmax-15.c
b/gcc/testsuite/gcc.dg/tree-ssa/minmax-15.c
index 8a39871c938..6731f91e6c3 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/minmax-15.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/minmax-15.c
@@ -30,5 +30,6 @@ main (void)
return 0;
}
-/* { dg-final { scan-tree-dump-times "MIN_EXPR" 3 "phiopt1" } } */
+/* There should only be two MIN_EXPR left, the 3rd one was removed. */
+/* { dg-final { scan-tree-dump-times "MIN_EXPR" 2 "phiopt1" } } */
/* { dg-final { scan-tree-dump-times "MAX_EXPR" 0 "phiopt1" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/minmax-16.c
b/gcc/testsuite/gcc.dg/tree-ssa/minmax-16.c
index 623b12b3f74..094364e6424 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/minmax-16.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/minmax-16.c
@@ -25,11 +25,8 @@ main (void)
return 0;
}
-/* After phiopt1, there really should be only 3 MIN_EXPR in the IR (including
debug statements).
- But the way phiopt does not cleanup the CFG all the time, the PHI might
still reference the
- alternative bb's moved statement.
- Note in the end, we do dce the statement and other debug statements to end
up with only 2 MIN_EXPR.
- So check that too. */
-/* { dg-final { scan-tree-dump-times "MIN_EXPR" 4 "phiopt1" } } */
+/* After phiopt1, will be only 2 MIN_EXPR in the IR (including debug
statements). */
+/* xk will only have the final result so the extra debug info does not change
anything. */
+/* { dg-final { scan-tree-dump-times "MIN_EXPR" 2 "phiopt1" } } */
/* { dg-final { scan-tree-dump-times "MIN_EXPR" 2 "optimized" } } */
/* { dg-final { scan-tree-dump-times "MAX_EXPR" 0 "phiopt1" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/minmax-3.c
b/gcc/testsuite/gcc.dg/tree-ssa/minmax-3.c
index 2af10776346..521afe3e4d9 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/minmax-3.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/minmax-3.c
@@ -25,5 +25,5 @@ main (void)
return 0;
}
-/* { dg-final { scan-tree-dump-times "MIN_EXPR" 3 "phiopt1" } } */
+/* { dg-final { scan-tree-dump-times "MIN_EXPR" 2 "phiopt1" } } */
/* { dg-final { scan-tree-dump-times "MAX_EXPR" 0 "phiopt1" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/minmax-4.c
b/gcc/testsuite/gcc.dg/tree-ssa/minmax-4.c
index 973f39bfed3..49e27185b5e 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/minmax-4.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/minmax-4.c
@@ -26,4 +26,4 @@ main (void)
}
/* { dg-final { scan-tree-dump-times "MIN_EXPR" 0 "phiopt1" } } */
-/* { dg-final { scan-tree-dump-times "MAX_EXPR" 3 "phiopt1" } } */
+/* { dg-final { scan-tree-dump-times "MAX_EXPR" 2 "phiopt1" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/minmax-5.c
b/gcc/testsuite/gcc.dg/tree-ssa/minmax-5.c
index 34e4e720511..194c881cc98 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/minmax-5.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/minmax-5.c
@@ -25,5 +25,5 @@ main (void)
return 0;
}
-/* { dg-final { scan-tree-dump-times "MIN_EXPR" 2 "phiopt1" } } */
+/* { dg-final { scan-tree-dump-times "MIN_EXPR" 1 "phiopt1" } } */
/* { dg-final { scan-tree-dump-times "MAX_EXPR" 1 "phiopt1" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/minmax-8.c
b/gcc/testsuite/gcc.dg/tree-ssa/minmax-8.c
index 0160e573fef..d5cb53145ea 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/minmax-8.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/minmax-8.c
@@ -26,4 +26,4 @@ main (void)
}
/* { dg-final { scan-tree-dump-times "MIN_EXPR" 1 "phiopt1" } } */
-/* { dg-final { scan-tree-dump-times "MAX_EXPR" 2 "phiopt1" } } */
+/* { dg-final { scan-tree-dump-times "MAX_EXPR" 1 "phiopt1" } } */
diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
index 65b3deea34a..311423efeb5 100644
--- a/gcc/tree-ssa-phiopt.cc
+++ b/gcc/tree-ssa-phiopt.cc
@@ -82,6 +82,25 @@ single_non_singleton_phi_for_edges (gimple_seq seq, edge e0,
edge e1)
return phi;
}
+/* For each PHI in BB, copy the argument associated with SRC_E to TGT_E. */
+
+static void
+copy_phi_args (basic_block bb, edge src_e, edge tgt_e)
+{
+ gphi_iterator gsi;
+ int src_indx = src_e->dest_idx;
+
+ for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+ {
+ gphi *phi = gsi.phi ();
+ tree def = gimple_phi_arg_def (phi, src_indx);
+ location_t locus = gimple_phi_arg_location (phi, src_indx);
+
+ add_phi_arg (phi, def, tgt_e, locus);
+ }
+}
+
+
/* Replace PHI node element whose edge is E in block BB with variable NEW.
Remove the edge from COND_BLOCK which does not lead to BB (COND_BLOCK
is known to have two edges, one of which must reach BB). */
@@ -94,6 +113,7 @@ replace_phi_edge_with_variable (basic_block cond_block,
basic_block bb = gimple_bb (phi);
gimple_stmt_iterator gsi;
tree phi_result = PHI_RESULT (phi);
+ bool deleteboth = false;
/* Duplicate range info if they are the only things setting the target PHI.
This is needed as later on, the new_tree will be replacing
@@ -137,7 +157,14 @@ replace_phi_edge_with_variable (basic_block cond_block,
keep_edge = EDGE_SUCC (cond_block, 1);
}
else if ((keep_edge = find_edge (cond_block, e->src)))
- ;
+ {
+ basic_block bb1 = EDGE_SUCC (cond_block, 0)->dest;
+ basic_block bb2 = EDGE_SUCC (cond_block, 1)->dest;
+ if (single_pred_p (bb1) && single_pred_p (bb2)
+ && single_succ_p (bb1) && single_succ_p (bb2)
+ && empty_block_p (bb1) && empty_block_p (bb2))
+ deleteboth = true;
+ }
else
gcc_unreachable ();
@@ -148,6 +175,28 @@ replace_phi_edge_with_variable (basic_block cond_block,
e->probability = profile_probability::always ();
delete_basic_block (edge_to_remove->dest);
+ /* Eliminate the COND_EXPR at the end of COND_BLOCK. */
+ gsi = gsi_last_bb (cond_block);
+ gsi_remove (&gsi, true);
+ }
+ else if (deleteboth)
+ {
+ basic_block bb1 = EDGE_SUCC (cond_block, 0)->dest;
+ basic_block bb2 = EDGE_SUCC (cond_block, 1)->dest;
+
+ edge newedge = redirect_edge_and_branch (keep_edge, bb);
+ /* no new edge should be the same. */
+ gcc_assert (newedge == keep_edge);
+ keep_edge->flags |= EDGE_FALLTHRU;
+ keep_edge->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE);
+ keep_edge->probability = profile_probability::always ();
+ /* Copy the edge's phi entry from the old one */
+ copy_phi_args(bb, e, keep_edge);
+
+ /* Delete the old 2 empty basic blocks */
+ delete_basic_block (bb1);
+ delete_basic_block (bb2);
+
/* Eliminate the COND_EXPR at the end of COND_BLOCK. */
gsi = gsi_last_bb (cond_block);
gsi_remove (&gsi, true);
--
2.31.1
