Mario1159/verilator
1
0
Fork 0
forked from github/verilator
Code Pull Requests Releases 1 Activity

Fix severe runtime performance bug in certain foreach loops.

Browse Source
This commit is contained in:
John Coiner 2018-03-15 08:59:52 -04:00
parent 2d580e6939
commit f55040a38b
4 changed files with 36 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
Changes
View File

@ -16,6 +16,8 @@ The contributors that suggested a given feature are shown in []. Thanks!
*** Add --no-debug-leak to reduce memory use under debug. [John Coiner]
**** Fix severe runtime performance bug in certain foreach loops. [John Coiner]
**** On convergence errors, show activity. [John Coiner]
**** Fix GCC 8.0 issues, bug1273.

34
src/V3LinkParse.cpp
View File

@ -340,6 +340,7 @@ private:
FileLine* fl = varsp->fileline();
AstNode* varp = new AstVar(fl, AstVarType::BLOCKTEMP,
varsp->name(), nodep->findSigned32DType());
// These will be the left and right dimensions of the array:
AstNode* leftp = new AstAttrOf(fl, AstAttrType::DIM_LEFT,
new AstVarRef(fl, arrayp->name(), false),
new AstConst(fl, dimension));
@ -347,19 +348,26 @@ private:
new AstVarRef(fl, arrayp->name(), false),
new AstConst(fl, dimension));
AstNode* stmtsp = varp;
stmtsp->addNext(new AstAssign(fl, new AstVarRef(fl, varp->name(), true), leftp));
AstNode* comparep =
new AstCond(fl, new AstLte(fl, leftp->cloneTree(true), rightp->cloneTree(true)),
// left increments up to right
new AstLte(fl, new AstVarRef(fl, varp->name(), false), rightp->cloneTree(true)),
// left decrements down to right
new AstGte(fl, new AstVarRef(fl, varp->name(), false), rightp));
AstNode* incp =
new AstAssign(fl, new AstVarRef(fl, varp->name(), true),
new AstAdd(fl, new AstVarRef(fl, varp->name(), false),
new AstNegate(fl, new AstAttrOf(fl, AstAttrType::DIM_INCREMENT,
new AstVarRef(fl, arrayp->name(), false),
new AstConst(fl, dimension)))));
// Assign left-dimension into the loop var:
stmtsp->addNext(new AstAssign
(fl, new AstVarRef(fl, varp->name(), true), leftp));
// This will turn into a bool constant, indicating whether
// we count the loop variable up or down:
AstNode* countupp = new AstLte(fl, leftp->cloneTree(true),
rightp->cloneTree(true));
AstNode* comparep = new AstCond(
fl, countupp->cloneTree(true),
// Left increments up to right
new AstLte(fl, new AstVarRef(fl, varp->name(), false),
rightp->cloneTree(true)),
// Left decrements down to right
new AstGte(fl, new AstVarRef(fl, varp->name(), false), rightp));
AstNode* incp = new AstAssign(
fl, new AstVarRef(fl, varp->name(), true),
new AstAdd(fl, new AstVarRef(fl, varp->name(), false),
new AstCond(fl, countupp,
new AstConst(fl, 1),
new AstConst(fl, -1))));
stmtsp->addNext(new AstWhile(fl, comparep, newp, incp));
newp = new AstBegin(nodep->fileline(),"",stmtsp);
dimension--;

1
test_regress/t/t_foreach.pl
View File

@ -8,6 +8,7 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
# Version 2.0.
compile (
verilator_flags2 => ['--assert']
);
execute (

12
test_regress/t/t_foreach.v
View File

@ -13,12 +13,24 @@ module t (/*AUTOARG*/);
reg [63:0] sum;
reg [2:1] [4:3] array [5:6] [7:8];
reg [1:2] [3:4] larray [6:5] [8:7];
bit [31:0] depth1_array [0:0];
function [63:0] crc (input [63:0] sum, input [31:0] a, input [31:0] b, input [31:0] c, input [31:0] d);
crc = {sum[62:0],sum[63]} ^ {4'b0,a[7:0], 4'h0,b[7:0], 4'h0,c[7:0], 4'h0,d[7:0]};
endfunction
initial begin
sum = 0;
foreach (depth1_array[index]) begin
sum = crc(sum, index, 0, 0, 0);
// Ensure the index never goes out of bounds.
// We used to get this wrong for an array of depth 1.
assert (index != -1);
assert (index != 1);
end
`checkh(sum, 64'h0);
sum = 0;
foreach (array[a]) begin
sum = crc(sum, a, 0, 0, 0);