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Fix wrong SRA with VIEW_CONVERT_EXPR and reverse SSO 

Most cases of VIEW_CONVERT_EXPRs involving reverse scalar storage order are
disqualified for SRA because they are storage_order_barrier_p, but you can
still have a VIEW_CONVERT_EXPR to a regular composite type being applied to
a component of a record type with reverse scalar storage order.

In this case the bypass for !useless_type_conversion_p in sra_modify_assign,
albeit already heavily guarded, triggers and may generate wrong code, so the
patch makes sure that it does only when the SSO is the same on both side.

gcc/
	* tree-sra.cc (sra_modify_assign): Check that scalar storage order
	is the same on the LHS and RHS before rewriting one with the model
	of the other.
gcc/testsuite/
	* gnat.dg/sso17.adb: New test.
This commit is contained in:
Eric Botcazou 2022-05-13 11:15:08 +02:00
parent c77e4873b1
commit 7b844206ec
2 changed files with 56 additions and 23 deletions
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34
gcc/testsuite/gnat.dg/sso17.adb Normal file
View File

@ -0,0 +1,34 @@
-- { dg-do run }
-- { dg-options "-gnatws -O" }
with System;
procedure SSO17 is
type My_Float is new Float range 0.0 .. 359.99;
type Rec is record
Az : My_Float;
El : My_Float;
end record;
for Rec'Bit_Order use System.High_Order_First;
for Rec'Scalar_Storage_Order use System.High_Order_First;
R : Rec;
procedure Is_True (B : Boolean);
pragma No_Inline (Is_True);
procedure Is_True (B : Boolean) is
begin
if not B then
raise Program_Error;
end if;
end;
begin
R := (Az => 1.1, El => 2.2);
Is_True (R.Az'Valid);
R := (Az => 3.3, El => 4.4);
Is_True (R.Az'Valid);
end;

45
gcc/tree-sra.cc
View File

@ -4270,32 +4270,31 @@ sra_modify_assign (gimple *stmt, gimple_stmt_iterator *gsi)
sra_stats.exprs++;
}
if (modify_this_stmt)
if (modify_this_stmt
&& !useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (rhs)))
{
/* If we can avoid creating a VIEW_CONVERT_EXPR, then do so.
??? This should move to fold_stmt which we simply should
call after building a VIEW_CONVERT_EXPR here. */
if (AGGREGATE_TYPE_P (TREE_TYPE (lhs))
&& TYPE_REVERSE_STORAGE_ORDER (TREE_TYPE (lhs)) == racc->reverse
&& !contains_bitfld_component_ref_p (lhs))
{
lhs = build_ref_for_model (loc, lhs, 0, racc, gsi, false);
gimple_assign_set_lhs (stmt, lhs);
}
else if (lacc
&& AGGREGATE_TYPE_P (TREE_TYPE (rhs))
&& TYPE_REVERSE_STORAGE_ORDER (TREE_TYPE (rhs)) == lacc->reverse
&& !contains_vce_or_bfcref_p (rhs))
rhs = build_ref_for_model (loc, rhs, 0, lacc, gsi, false);
if (!useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (rhs)))
{
/* If we can avoid creating a VIEW_CONVERT_EXPR do so.
??? This should move to fold_stmt which we simply should
call after building a VIEW_CONVERT_EXPR here. */
if (AGGREGATE_TYPE_P (TREE_TYPE (lhs))
&& !contains_bitfld_component_ref_p (lhs))
{
lhs = build_ref_for_model (loc, lhs, 0, racc, gsi, false);
gimple_assign_set_lhs (stmt, lhs);
}
else if (lacc
&& AGGREGATE_TYPE_P (TREE_TYPE (rhs))
&& !contains_vce_or_bfcref_p (rhs))
rhs = build_ref_for_model (loc, rhs, 0, lacc, gsi, false);
if (!useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (rhs)))
{
rhs = fold_build1_loc (loc, VIEW_CONVERT_EXPR, TREE_TYPE (lhs),
rhs);
if (is_gimple_reg_type (TREE_TYPE (lhs))
&& TREE_CODE (lhs) != SSA_NAME)
force_gimple_rhs = true;
}
rhs = fold_build1_loc (loc, VIEW_CONVERT_EXPR, TREE_TYPE (lhs), rhs);
if (is_gimple_reg_type (TREE_TYPE (lhs))
&& TREE_CODE (lhs) != SSA_NAME)
force_gimple_rhs = true;
}
}