Hi,
As reported on PR104498, the issue here is that when
compare_base_symbol_refs swaps x and y but doesn't take that into
account when computing the distance.
This patch makes sure that if x and y are swapped, we correct the
distance computation by multiplying it by -1 to end up with the correct
expected result of the original Y_BASE - X_BASE.
Bootstrapped and regression tested on aarch64-none-linux.
OK for trunk?
gcc/ChangeLog:
PR middle-end/104498
* alias.cc (compare_base_symbol_refs): Correct distance
computation when
swapping x and y.
diff --git a/gcc/alias.cc b/gcc/alias.cc
index
3fd71cff2e2b488bc39fcf7d937e118b96f491ab..8c08452e0acfcbf1bfd8fd2e8cd420b5b929d6b4
100644
--- a/gcc/alias.cc
+++ b/gcc/alias.cc
@@ -2195,6 +2195,7 @@ compare_base_symbol_refs (const_rtx x_base, const_rtx
y_base,
tree x_decl = SYMBOL_REF_DECL (x_base);
tree y_decl = SYMBOL_REF_DECL (y_base);
bool binds_def = true;
+ bool swap = false;
if (XSTR (x_base, 0) == XSTR (y_base, 0))
return 1;
@@ -2204,6 +2205,7 @@ compare_base_symbol_refs (const_rtx x_base, const_rtx
y_base,
{
if (!x_decl)
{
+ swap = true;
std::swap (x_decl, y_decl);
std::swap (x_base, y_base);
}
@@ -2238,8 +2240,8 @@ compare_base_symbol_refs (const_rtx x_base, const_rtx
y_base,
if (SYMBOL_REF_BLOCK (x_base) != SYMBOL_REF_BLOCK (y_base))
return 0;
if (distance)
- *distance += (SYMBOL_REF_BLOCK_OFFSET (y_base)
- - SYMBOL_REF_BLOCK_OFFSET (x_base));
+ *distance += (swap ? -1 : 1) * (SYMBOL_REF_BLOCK_OFFSET (y_base)
+ - SYMBOL_REF_BLOCK_OFFSET (x_base));
return binds_def ? 1 : -1;
}
/* Either the symbols are equal (via aliasing) or they refer to
