Commit Graph

16 Commits

Author SHA1 Message Date
Arnold Schwaighofer 0caddfc731 LoopVectorize: External uses must use the last value in a reduction cycle
Otherwise, we don't perform operations that would have been performed on
the scalar version.

Fixes PR17498.

llvm-svn: 192133
2013-10-07 21:05:43 +00:00
Stephen Lin c1c7a1309c Update Transforms tests to use CHECK-LABEL for easier debugging. No functionality change.
This update was done with the following bash script:

  find test/Transforms -name "*.ll" | \
  while read NAME; do
    echo "$NAME"
    if ! grep -q "^; *RUN: *llc" $NAME; then
      TEMP=`mktemp -t temp`
      cp $NAME $TEMP
      sed -n "s/^define [^@]*@\([A-Za-z0-9_]*\)(.*$/\1/p" < $NAME | \
      while read FUNC; do
        sed -i '' "s/;\(.*\)\([A-Za-z0-9_]*\):\( *\)@$FUNC\([( ]*\)\$/;\1\2-LABEL:\3@$FUNC(/g" $TEMP
      done
      mv $TEMP $NAME
    fi
  done

llvm-svn: 186268
2013-07-14 01:42:54 +00:00
Arnold Schwaighofer a92eeebde8 LoopVectorizer: Disallow reductions whose header phi is used outside the loop
If an outside loop user of the reduction value uses the header phi node we
cannot just reduce the vectorized phi value in the vector code epilog because
we would loose VF-1 reductions.

lp:
  p = phi (0, lv)
  lv = lv + 1
  ...
  brcond , lp, outside

outside:
  usr = add 0, p

(Say the loop iterates two times, the value of p coming out of the loop is one).

We cannot just transform this to:

vlp:
  p = phi (<0,0>, lv)
  lv = lv + <1,1>
  ..
  brcond , lp, outside

outside:
  p_reduced = p[0] + [1];
  usr = add 0, p_reduced

(Because the original loop iterated two times the vectorized loop would iterate
one time, but p_reduced ends up being zero instead of one).

We would have to execute VF-1 iterations in the scalar remainder loop in such
cases. For now, just disable vectorization.

PR16522

llvm-svn: 186256
2013-07-13 19:09:29 +00:00
Arnold Schwaighofer 3610139ac5 LoopVectorizer: Improve reduction variable identification
The two nested loops were confusing and also conservative in identifying
reduction variables. This patch replaces them by a worklist based approach.

llvm-svn: 181369
2013-05-07 21:55:37 +00:00
Nadav Rotem 30a65bc39e Remove the -licm pass from the loop vectorizer test because the loop vectorizer does it now.
llvm-svn: 171930
2013-01-09 01:20:59 +00:00
Nadav Rotem f19d515316 Fix a typo. Remove the duplicated test.
llvm-svn: 171584
2013-01-05 01:17:46 +00:00
Nadav Rotem e9f5bfd5e9 iLoopVectorize: Non commutative operators can be used as reduction variables as long as the reduction chain is used in the LHS.
PR14803.

llvm-svn: 171583
2013-01-05 01:15:47 +00:00
Nadav Rotem 6d9dafe3ff Force a fixed unroll count on the target independent tests.
This should fix clang-native-arm-cortex-a9. Thanks Renato.

llvm-svn: 171582
2013-01-05 00:58:48 +00:00
Paul Redmond 874f01e956 Do not vectorize loops with subtraction reductions
Since subtraction does not commute the loop vectorizer incorrectly vectorizes
reductions such as x = A[i] - x.

Disabling for now.

llvm-svn: 171537
2013-01-04 22:10:16 +00:00
Benjamin Kramer f0e5d2f032 LoopVectorize: Emit reductions as log2(vectorsize) shuffles + vector ops instead of scalar operations.
For example on x86 with SSE4.2 a <8 x i8> add reduction becomes
	movdqa	%xmm0, %xmm1
	movhlps	%xmm1, %xmm1            ## xmm1 = xmm1[1,1]
	paddw	%xmm0, %xmm1
	pshufd	$1, %xmm1, %xmm0        ## xmm0 = xmm1[1,0,0,0]
	paddw	%xmm1, %xmm0
	phaddw	%xmm0, %xmm0
	pextrb	$0, %xmm0, %edx

instead of
	pextrb	$2, %xmm0, %esi
	pextrb	$0, %xmm0, %edx
	addb	%sil, %dl
	pextrb	$4, %xmm0, %esi
	addb	%dl, %sil
	pextrb	$6, %xmm0, %edx
	addb	%sil, %dl
	pextrb	$8, %xmm0, %esi
	addb	%dl, %sil
	pextrb	$10, %xmm0, %edi
	pextrb	$14, %xmm0, %edx
	addb	%sil, %dil
	pextrb	$12, %xmm0, %esi
	addb	%dil, %sil
	addb	%sil, %dl

llvm-svn: 170439
2012-12-18 18:40:20 +00:00
Nadav Rotem 4cb8cdab5e LoopVectorize: Preserve NSW, NUW and IsExact flags.
llvm-svn: 167174
2012-10-31 21:40:39 +00:00
Nadav Rotem b3e8e688da LoopVectorize: Fix a bug in the initialization of reduction variables. AND needs to start at all-one
while XOR, and OR need to start at zero.

llvm-svn: 167032
2012-10-30 18:12:36 +00:00
Nadav Rotem 5ffb049a55 Add support for additional reduction variables: AND, OR, XOR.
Patch by Paul Redmond <paul.redmond@intel.com>.

llvm-svn: 166649
2012-10-25 00:08:41 +00:00
Nadav Rotem a721b21c64 LoopVectorizer: Add a basic cost model which uses the VTTI interface.
llvm-svn: 166620
2012-10-24 20:36:32 +00:00
Nadav Rotem c1679a95b6 Add support for reduction variables that do not start at zero.
This is important for nested-loop reductions such as :

In the innermost loop, the induction variable does not start with zero:

for (i = 0 .. n)
 for (j = 0 .. m)
  sum += ...

llvm-svn: 166387
2012-10-21 05:52:51 +00:00
Nadav Rotem 4f7f72702b Vectorizer: Add support for loop reductions.
For example:

  for (i=0; i<n; i++)
   sum += A[i] +  B[i] + i;

llvm-svn: 166351
2012-10-19 23:05:40 +00:00