Hi,
The attached patch
1. enables vectorization of BAND, BXOR and SHL operations as well as adds
support for expanding vectorized shift-left operation.
2. fixes a bug in vectorizing expressions with negative coefficient. An example
program is:
int a[];
double b[], x;
void foo (void) {
int i;
for (i = 0; i < 1000; i++)
b[i] += a[1000-i] * x;
}
Note that for "(double)a[1000-i]":
- the coefficient of the loop index is -1 (so, still unit-strided),
- and sizeof(a[*]) == 4
There are only *TWO* elements encapsulated in a single vector. However,
current SIMD implementation takes for granted there
are four elements involved. On the other hand, since the coefficient is
negative, the elements of vector need to be reversed.
There was no OPCODE capable of reversing two 4-byte elements, hence
V8I4V8I4SHUFFLE is introduced.
The wrong vectorized WHIRL of the expression was:
1 U8LDA 0 <1,52,a> T<57,anon_ptr.,8>
2 U4INTCONST 0 (0x0)
3 I4INTCONST 997 (0x3e5) /* wrong starting addr */
4 I4I4LDID 49 <1,4,.preg_I4> T<4,.predef_I4,4> # i
5 I4SUB
6 U8ARRAY 1 4
7 V8I4V8I4ILOAD 0 T<4,.predef_I4,4> T<58,anon_ptr.,8>
8 V16I4V16I4SHUFFLE 0 /* wrong shuffle */
9 V16F8V8I4CVT
with the fix it is:
1 U8LDA 0 <1,52,a> T<57,anon_ptr.,8>
2 U4INTCONST 0 (0x0)
3 I4INTCONST 999 (0x3e7)
4 I4I4LDID 49 <1,4,.preg_I4> T<4,.predef_I4,4> # i
5 I4SUB
6 U8ARRAY 1 4
7 V8I4V8I4ILOAD 0 T<4,.predef_I4,4> T<58,anon_ptr.,8>
8 V8I4V8I4SHUFFLE 0
9 V16F8V8I4CVT
Can a gatekeeper please review this patch?
Thanks,
Pallavi
vectorizer.p
Description: vectorizer.p
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