Commit Graph

5 Commits

Author SHA1 Message Date
Sanjay Patel 9bba75084b [InstCombine] transform bitcasted bitwise logic ops with constants (PR26702)
Given that we're not actually reducing the instruction count in the included
regression tests, I think we would call this a canonicalization step.

The motivation comes from the example in PR26702:
https://llvm.org/bugs/show_bug.cgi?id=26702

If we hoist the bitwise logic ahead of the bitcast, the previously unoptimizable
example of:

define <4 x i32> @is_negative(<4 x i32> %x) {
  %lobit = ashr <4 x i32> %x, <i32 31, i32 31, i32 31, i32 31>
  %not = xor <4 x i32> %lobit, <i32 -1, i32 -1, i32 -1, i32 -1>
  %bc = bitcast <4 x i32> %not to <2 x i64>
  %notnot = xor <2 x i64> %bc, <i64 -1, i64 -1>
  %bc2 = bitcast <2 x i64> %notnot to <4 x i32>
  ret <4 x i32> %bc2
}

Simplifies to the expected:

define <4 x i32> @is_negative(<4 x i32> %x) {
  %lobit = ashr <4 x i32> %x, <i32 31, i32 31, i32 31, i32 31>
  ret <4 x i32> %lobit
}

Differential Revision: http://reviews.llvm.org/D17583

llvm-svn: 262645
2016-03-03 19:19:04 +00:00
Sanjay Patel 8ad2c4eeb0 add tests to show missing bitcasted logic transform
llvm-svn: 261799
2016-02-24 22:31:18 +00:00
Richard Sandiford feb34713d5 Fix big-endian handling of integer-to-vector bitcasts in InstCombine
These functions used to assume that the lsb of an integer corresponds
to vector element 0, whereas for big-endian it's the other way around:
the msb is in the first element and the lsb is in the last element.

Fixes MultiSource/Benchmarks/mediabench/gsm/toast for z.

llvm-svn: 188155
2013-08-12 07:26:09 +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
Ulrich Weigand b1e02b2af2 Add test case for commit r178031.
llvm-svn: 178038
2013-03-26 17:30:02 +00:00