**diff options**

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 | [Ada] Casing style on record components (diff) | |

download | gcc-88f7b07de7579251f5134b65dad406fdfda3d057.tar.gz gcc-88f7b07de7579251f5134b65dad406fdfda3d057.tar.bz2 gcc-88f7b07de7579251f5134b65dad406fdfda3d057.tar.xz |

[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 b39b2a7136c..d4a62ace9c2 100644 --- a/gcc/ada/exp_pakd.adb +++ b/gcc/ada/exp_pakd.adb | |||

@@ -1930,9 +1930,17 @@ package body Exp_Pakd is | |||

1930 | -- modular case we guarantee that the unused bits are always zeroes. | 1930 | -- modular case we guarantee that the unused bits are always zeroes. |

1931 | -- We do have to compare the lengths because we could be comparing | 1931 | -- We do have to compare the lengths because we could be comparing |

1932 | -- two different subtypes of the same base type. We can only do this | 1932 | -- two different subtypes of the same base type. We can only do this |

1933 | -- if the PATs on both sides are the same. | 1933 | -- if the PATs on both sides are modular (in which case they are |

1934 | -- necessarily structurally the same -- same Modulus and so on); | ||

1935 | -- otherwise, we have a case where the right operand is not of | ||

1936 | -- compile time known size. | ||

1937 | |||

1938 | if Is_Modular_Integer_Type (PAT) | ||

1939 | and then Is_Modular_Integer_Type (Etype (R)) | ||

1940 | then | ||

1941 | pragma Assert (RM_Size (Etype (R)) = RM_Size (PAT)); | ||

1942 | pragma Assert (Modulus (Etype (R)) = Modulus (PAT)); | ||

1934 | 1943 | ||

1935 | if Is_Modular_Integer_Type (PAT) and then PAT = Etype (R) then | ||

1936 | Rewrite (N, | 1944 | Rewrite (N, |

1937 | Make_And_Then (Loc, | 1945 | Make_And_Then (Loc, |

1938 | Left_Opnd => | 1946 | Left_Opnd => |

diff --git a/gcc/ada/exp_pakd.ads b/gcc/ada/exp_pakd.ads index f61ae089730..e80787acdd7 100644 --- a/gcc/ada/exp_pakd.ads +++ b/gcc/ada/exp_pakd.ads | |||

@@ -41,7 +41,8 @@ package Exp_Pakd is | |||

41 | 41 | ||

42 | -- This packed array type has the name xxxPn, where xxx is the name | 42 | -- This packed array type has the name xxxPn, where xxx is the name |

43 | -- of the packed type, and n is the component size. The expanded | 43 | -- of the packed type, and n is the component size. The expanded |

44 | -- declaration declares a type that is one of the following: | 44 | -- declaration declares a type that is one of the following (sizes |

45 | -- below are in bytes): | ||

45 | 46 | ||

46 | -- For an unconstrained array with component size 1,2,4 or any other | 47 | -- For an unconstrained array with component size 1,2,4 or any other |

47 | -- odd component size. These are the cases in which we do not need | 48 | -- odd component size. These are the cases in which we do not need |

@@ -49,10 +50,10 @@ package Exp_Pakd is | |||

49 | 50 | ||

50 | -- type xxxPn is new Packed_Bytes1; | 51 | -- type xxxPn is new Packed_Bytes1; |

51 | 52 | ||

52 | -- For an unconstrained array with component size that is divisible | 53 | -- For an unconstrained array with component size greater than 2, that is |

53 | -- by 2, but not divisible by 4 (other than 2 itself). These are the | 54 | -- divisible by 2, but not divisible by 4. These are the cases in which |

54 | -- cases in which we can generate better code if the underlying array | 55 | -- we can generate better code if the underlying array is 2-byte aligned |

55 | -- is 2-byte aligned (see System.Pack_14 in file s-pack14 for example). | 56 | -- (see System.Pack_14 in file s-pack14 for example). |

56 | 57 | ||

57 | -- type xxxPn is new Packed_Bytes2; | 58 | -- type xxxPn is new Packed_Bytes2; |

58 | 59 | ||

@@ -942,7 +943,7 @@ package Exp_Pakd is | |||

942 | -- N is an N_Op_Eq node where the operands are packed arrays whose | 943 | -- N is an N_Op_Eq node where the operands are packed arrays whose |

943 | -- representation is an array-of-bytes type (the case where a modular | 944 | -- representation is an array-of-bytes type (the case where a modular |

944 | -- type is used for the representation does not require any special | 945 | -- type is used for the representation does not require any special |

945 | -- handling, because in the modular case, unused bits are zeroes. | 946 | -- handling, because in the modular case, unused bits are zeroes). |

946 | 947 | ||

947 | procedure Expand_Packed_Not (N : Node_Id); | 948 | procedure Expand_Packed_Not (N : Node_Id); |

948 | -- N is an N_Op_Not node where the operand is packed array of Boolean | 949 | -- N is an N_Op_Not node where the operand is packed array of Boolean |