In some cases phi sources are all mixed-up.
For example, on the following case:
static int foo(void)
{
int i = 6;
int j = 1;
do {
if (i != 6)
i++;
i++;
} while (i != j);
return j;
}
test-linearize returns something like:
.L0:
phisrc.32 %phi3(i) <- $6
phisrc.32 %phi7(i) <- $6
br .L1
.L1:
phi.32 %r1(i) <- %phi7(i), %phi8(i)
setne.32 %r2 <- %r1(i), $6
br %r2, .L4, .L5
.L4:
add.32 %r4 <- %r1(i), $1
phisrc.32 %phi5(i) <- %r4
br .L5
.L5:
phi.32 %r5 <- %phi3(i), %phi4(i), %phi5(i)
add.32 %r6(i) <- %r5, $1
phisrc.32 %phi4(i) <- %r6(i)
phisrc.32 %phi8(i) <- %r6(i)
setne.32 %r8 <- %r6(i), $1
br %r8, .L1, .L6
.L6:
ret.32 $1
The phi-node in .L5 is odd: .L5 has 2 parents (.L1 & .L4), we thus
expect to have 2 phisrc, one in .L1 and another one in .L4. There is
other oddities with phisrc: the redundant ones in .L0 and .L5.
In fact there is some sort of mixup with the phi & phisrc of .L1
and the ones in .L5 (and investigation showed it doesn't come from
further simplification phase but are already there since the creation
of these phi & phisrc).
The fix essentially consists in a revert of
(commit cf07903a "Don't bother finding dominating loads if we have to search multiple paths")
which was already partially reverted in
(commit c040f2e0 "Remove incorrect left-over from (not useful) old load-load dominance trials.")
We then get the more expected:
.L0:
phisrc.32 %phi6(i) <- $6
br .L1
.L1:
phi.32 %r1(i) <- %phi6(i), %phi7(i)
setne.32 %r2 <- %r1(i), $6
phisrc.32 %phi3(i) <- %r1(i)
br %r2, .L4, .L5
.L4:
add.32 %r4 <- %r1(i), $1
phisrc.32 %phi4(i) <- %r4
br .L5
.L5:
phi.32 %r5 <- %phi3(i), %phi4(i)
add.32 %r6(i) <- %r5, $1
phisrc.32 %phi7(i) <- %r6(i)
setne.32 %r8 <- %r6(i), $1
br %r8, .L1, .L6
.L6:
ret.32 $1
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
---
flow.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)
diff --git a/flow.c b/flow.c
index d8e253b1..ef07b6db 100644
--- a/flow.c
+++ b/flow.c
@@ -329,15 +329,13 @@ static int phisrc_in_bb(struct pseudo_list *list, struct basic_block *bb)
static int find_dominating_parents(pseudo_t pseudo, struct instruction *insn,
struct basic_block *bb, unsigned long generation, struct pseudo_list **dominators,
- int local, int loads)
+ int local)
{
struct basic_block *parent;
if (!bb->parents)
return !!local;
- if (bb_list_size(bb->parents) > 1)
- loads = 0;
FOR_EACH_PTR(bb->parents, parent) {
struct instruction *one;
struct instruction *br;
@@ -355,8 +353,6 @@ static int find_dominating_parents(pseudo_t pseudo, struct instruction *insn,
}
if (!dominance)
continue;
- if (one->opcode == OP_LOAD && !loads)
- continue;
goto found_dominator;
} END_FOR_EACH_PTR_REVERSE(one);
no_dominance:
@@ -364,7 +360,7 @@ no_dominance:
continue;
parent->generation = generation;
- if (!find_dominating_parents(pseudo, insn, parent, generation, dominators, local, loads))
+ if (!find_dominating_parents(pseudo, insn, parent, generation, dominators, local))
return 0;
continue;
@@ -467,7 +463,7 @@ found:
bb->generation = generation;
dominators = NULL;
- if (!find_dominating_parents(pseudo, insn, bb, generation, &dominators, local, 1))
+ if (!find_dominating_parents(pseudo, insn, bb, generation, &dominators, local))
return 0;
/* This happens with initial assignments to structures etc.. */
--
2.11.0
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