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Support 2D packed bit arrays in struct/union.

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This commit is contained in:
Peter Crozier 2020-06-09 13:52:09 +01:00
parent 01ec681373
commit f80b09fc58
1 changed files with 1 additions and 35 deletions
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36
frontends/ast/simplify.cc
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@ -383,43 +383,9 @@ static AstNode *node_int(int ival)
return AstNode::mkconst_int(ival, true); return AstNode::mkconst_int(ival, true);
} }
static AstNode *node_uint(uint ival)
{
return AstNode::mkconst_int(ival, false);
}
static unsigned int power_of_two(int n)
{
// iff n is a power of two then return the power, else return 0
// caller must ensure n > 1
log_assert(n > 1);
if (n & (n - 1)) {
// not a power of 2
return 0;
}
// brute force the shift
for (unsigned int i = 1; i < 32; i++) {
n >>= 1;
if (n & 1) {
return i;
}
}
return 0;
}
static AstNode *multiply_by_const(AstNode *expr_node, int stride) static AstNode *multiply_by_const(AstNode *expr_node, int stride)
{ {
// the stride is very likely a power of 2, e.g. 8 for bytes return new AstNode(AST_MUL, expr_node, node_int(stride));
// and so could be optimised with a shift
AstNode *node;
unsigned int shift;
if ((shift = power_of_two(stride)) > 0) {
node = new AstNode(AST_SHIFT_LEFT, expr_node, node_uint(shift));
}
else {
node = new AstNode(AST_MUL, expr_node, node_int(stride));
}
return node;
} }
static AstNode *offset_indexed_range(int offset, int stride, AstNode *left_expr, AstNode *right_expr) static AstNode *offset_indexed_range(int offset, int stride, AstNode *left_expr, AstNode *right_expr)