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llvm-project/llvm/test/Transforms/InstCombine/sub-xor.ll

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InstCombine: Canonicalize (2^n)-1 - x into (2^n)-1 ^ x iff x is known to be smaller than 2^n. This has the obvious advantage of being commutable and is always a win on x86 because const - x wastes a register there. On less weird architectures this may lead to a regression because other arithmetic doesn't fuse with it anymore. I'll address that problem in a followup. llvm-svn: 147254
2011-12-25 01:31:38 +08:00
; RUN: opt -instcombine -S < %s | FileCheck %s
define i32 @test1(i32 %x) nounwind {
%and = and i32 %x, 31
%sub = sub i32 63, %and
ret i32 %sub
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 $NAME fi done llvm-svn: 186268
2013-07-14 09:42:54 +08:00
; CHECK-LABEL: @test1(
InstCombine: Canonicalize (2^n)-1 - x into (2^n)-1 ^ x iff x is known to be smaller than 2^n. This has the obvious advantage of being commutable and is always a win on x86 because const - x wastes a register there. On less weird architectures this may lead to a regression because other arithmetic doesn't fuse with it anymore. I'll address that problem in a followup. llvm-svn: 147254
2011-12-25 01:31:38 +08:00
; CHECK-NEXT: and i32 %x, 31
; CHECK-NEXT: xor i32 %and, 63
; CHECK-NEXT: ret
}
ComputeMaskedBits: Make knownzero computation more aggressive for ctlz with undef zero. unsigned foo(unsigned x) { return 31 - __builtin_clz(x); } now compiles into a single "bsrl" instruction on x86. llvm-svn: 147255
2011-12-25 01:31:46 +08:00
declare i32 @llvm.ctlz.i32(i32, i1) nounwind readnone
define i32 @test2(i32 %x) nounwind {
%count = tail call i32 @llvm.ctlz.i32(i32 %x, i1 true) nounwind readnone
%sub = sub i32 31, %count
ret i32 %sub
Update Transforms tests to use CHECK-LABEL for easier debugging. No functionality change. This update was done with the following bash script: find test/Transforms -name "*.ll" | \ while read NAME; do echo "$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 $NAME fi done llvm-svn: 186268
2013-07-14 09:42:54 +08:00
; CHECK-LABEL: @test2(
ComputeMaskedBits: Make knownzero computation more aggressive for ctlz with undef zero. unsigned foo(unsigned x) { return 31 - __builtin_clz(x); } now compiles into a single "bsrl" instruction on x86. llvm-svn: 147255
2011-12-25 01:31:46 +08:00
; CHECK-NEXT: ctlz
; CHECK-NEXT: xor i32 %count, 31
; CHECK-NEXT: ret
}
InstCombine: Add a combine that turns (2^n)-1 ^ x back into (2^n)-1 - x iff x is smaller than 2^n and it fuses with a following add. This was intended to undo the sub canonicalization in cases where it's not profitable, but it also finds some cases on it's own. llvm-svn: 147256
2011-12-25 01:31:53 +08:00
define i32 @test3(i32 %x) nounwind {
%and = and i32 %x, 31
%sub = xor i32 31, %and
%add = add i32 %sub, 42
ret i32 %add
Update Transforms tests to use CHECK-LABEL for easier debugging. No functionality change. This update was done with the following bash script: find test/Transforms -name "*.ll" | \ while read NAME; do echo "$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 $NAME fi done llvm-svn: 186268
2013-07-14 09:42:54 +08:00
; CHECK-LABEL: @test3(
InstCombine: Add a combine that turns (2^n)-1 ^ x back into (2^n)-1 - x iff x is smaller than 2^n and it fuses with a following add. This was intended to undo the sub canonicalization in cases where it's not profitable, but it also finds some cases on it's own. llvm-svn: 147256
2011-12-25 01:31:53 +08:00
; CHECK-NEXT: and i32 %x, 31
InstCombine: Annotate sub with nsw when we prove it's safe We can prove that a 'sub' can be a 'sub nsw' under certain conditions: - The sign bits of the operands is the same. - Both operands have more than 1 sign bit. The subtraction cannot be a signed overflow in either case. llvm-svn: 216037
2014-08-20 07:36:30 +08:00
; CHECK-NEXT: sub nsw i32 73, %and
InstCombine: Add a combine that turns (2^n)-1 ^ x back into (2^n)-1 - x iff x is smaller than 2^n and it fuses with a following add. This was intended to undo the sub canonicalization in cases where it's not profitable, but it also finds some cases on it's own. llvm-svn: 147256
2011-12-25 01:31:53 +08:00
; CHECK-NEXT: ret
}
InstCombine: (X ^ signbit) + C -> X + (signbit ^ C) llvm-svn: 181249
2013-05-07 05:21:31 +08:00
define i32 @test4(i32 %x) nounwind {
%sub = xor i32 %x, 2147483648
%add = add i32 %sub, 42
ret i32 %add
Update Transforms tests to use CHECK-LABEL for easier debugging. No functionality change. This update was done with the following bash script: find test/Transforms -name "*.ll" | \ while read NAME; do echo "$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 09:42:54 +08:00
; CHECK-LABEL: @test4(
InstCombine: (X ^ signbit) + C -> X + (signbit ^ C) llvm-svn: 181249
2013-05-07 05:21:31 +08:00
; CHECK-NEXT: add i32 %x, -2147483606
; CHECK-NEXT: ret
}