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| author | Bob Duff <duff@adacore.com> | 2022-04-07 13:23:20 -0400 |
|---|---|---|
| committer | Pierre-Marie de Rodat <derodat@adacore.com> | 2022-05-19 14:05:29 +0000 |
| commit | 88f7b07de7579251f5134b65dad406fdfda3d057 (patch) | |
| tree | f1c8accae93142fd6cbcf5b10b07e29106b9dd06 /gcc | |
| parent | 5cc07f401a69f14638cfd37b27401e4e0fd8fc65 (diff) | |
| download | gcc-88f7b07de7579251f5134b65dad406fdfda3d057.zip gcc-88f7b07de7579251f5134b65dad406fdfda3d057.tar.gz gcc-88f7b07de7579251f5134b65dad406fdfda3d057.tar.bz2 | |
[Ada] Improve optimization of "=" on bit-packed arrays
This patch fixes a performance regression, introduced by a previous bug
fix. That fix had the unintended side effect of removing the
optimization in cases where the two operands are of two different
compiler-generated modular types.
gcc/ada/
* exp_pakd.adb (Expand_Packed_Eq): Replace the check for *same*
modular type, with a check for any modular type, and assert that
the two types have the same modulus and so on.
* exp_pakd.ads: Minor comment improvements.
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ada/exp_pakd.adb | 12 | ||||
| -rw-r--r-- | gcc/ada/exp_pakd.ads | 13 |
2 files changed, 17 insertions, 8 deletions
diff --git a/gcc/ada/exp_pakd.adb b/gcc/ada/exp_pakd.adb index b39b2a7..d4a62ac 100644 --- a/gcc/ada/exp_pakd.adb +++ b/gcc/ada/exp_pakd.adb @@ -1930,9 +1930,17 @@ package body Exp_Pakd is -- modular case we guarantee that the unused bits are always zeroes. -- We do have to compare the lengths because we could be comparing -- two different subtypes of the same base type. We can only do this - -- if the PATs on both sides are the same. + -- if the PATs on both sides are modular (in which case they are + -- necessarily structurally the same -- same Modulus and so on); + -- otherwise, we have a case where the right operand is not of + -- compile time known size. + + if Is_Modular_Integer_Type (PAT) + and then Is_Modular_Integer_Type (Etype (R)) + then + pragma Assert (RM_Size (Etype (R)) = RM_Size (PAT)); + pragma Assert (Modulus (Etype (R)) = Modulus (PAT)); - if Is_Modular_Integer_Type (PAT) and then PAT = Etype (R) then Rewrite (N, Make_And_Then (Loc, Left_Opnd => diff --git a/gcc/ada/exp_pakd.ads b/gcc/ada/exp_pakd.ads index f61ae08..e80787a 100644 --- a/gcc/ada/exp_pakd.ads +++ b/gcc/ada/exp_pakd.ads @@ -41,7 +41,8 @@ package Exp_Pakd is -- This packed array type has the name xxxPn, where xxx is the name -- of the packed type, and n is the component size. The expanded - -- declaration declares a type that is one of the following: + -- declaration declares a type that is one of the following (sizes + -- below are in bytes): -- For an unconstrained array with component size 1,2,4 or any other -- odd component size. These are the cases in which we do not need @@ -49,10 +50,10 @@ package Exp_Pakd is -- type xxxPn is new Packed_Bytes1; - -- For an unconstrained array with component size that is divisible - -- by 2, but not divisible by 4 (other than 2 itself). These are the - -- cases in which we can generate better code if the underlying array - -- is 2-byte aligned (see System.Pack_14 in file s-pack14 for example). + -- For an unconstrained array with component size greater than 2, that is + -- divisible by 2, but not divisible by 4. These are the cases in which + -- we can generate better code if the underlying array is 2-byte aligned + -- (see System.Pack_14 in file s-pack14 for example). -- type xxxPn is new Packed_Bytes2; @@ -942,7 +943,7 @@ package Exp_Pakd is -- N is an N_Op_Eq node where the operands are packed arrays whose -- representation is an array-of-bytes type (the case where a modular -- type is used for the representation does not require any special - -- handling, because in the modular case, unused bits are zeroes. + -- handling, because in the modular case, unused bits are zeroes). procedure Expand_Packed_Not (N : Node_Id); -- N is an N_Op_Not node where the operand is packed array of Boolean |