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optimize:
void a(int x) { if (((1<<x)&8)==0) b(); } into "x != 3", which occurs over 100 times in 403.gcc but in no other program in llvm-test. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119922 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -1699,14 +1699,6 @@ This should be optimized to a single compare. Testcase derived from gcc.
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//===---------------------------------------------------------------------===//
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Missed instcombine transformation:
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void b();
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void a(int x) { if (((1<<x)&8)==0) b(); }
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The shift should be optimized out. Testcase derived from gcc.
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//===---------------------------------------------------------------------===//
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Missed instcombine or reassociate transformation:
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int a(int a, int b) { return (a==12)&(b>47)&(b<58); }
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@ -1744,14 +1744,84 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
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// simplify this comparison. For example, (x&4) < 8 is always true.
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switch (I.getPredicate()) {
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default: llvm_unreachable("Unknown icmp opcode!");
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case ICmpInst::ICMP_EQ:
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case ICmpInst::ICMP_EQ: {
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if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max))
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return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext()));
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// If all bits are known zero except for one, then we know at most one
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// bit is set. If the comparison is against zero, then this is a check
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// to see if *that* bit is set.
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APInt Op0KnownZeroInverted = ~Op0KnownZero;
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if (~Op1KnownZero == 0 && Op0KnownZeroInverted.isPowerOf2()) {
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// If the LHS is an AND with the same constant, look through it.
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Value *LHS = 0;
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ConstantInt *LHSC = 0;
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if (!match(Op0, m_And(m_Value(LHS), m_ConstantInt(LHSC))) ||
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LHSC->getValue() != Op0KnownZeroInverted)
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LHS = Op0;
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// If the LHS is 1 << x, and we know the result is a power of 2 like 8,
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// then turn "((1 << x)&8) == 0" into "x == 3".
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Value *X = 0;
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if (match(LHS, m_Shl(m_One(), m_Value(X)))) {
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unsigned CmpVal = Op0KnownZeroInverted.countTrailingZeros();
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return new ICmpInst(ICmpInst::ICMP_EQ, X,
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ConstantInt::get(X->getType(), CmpVal));
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}
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// If the LHS is 8 >>u x, and we know the result is a power of 2 like 1,
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// then turn "((8 >>u x)&1) == 0" into "x == 3".
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ConstantInt *CI = 0;
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if (Op0KnownZeroInverted == 1 &&
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match(LHS, m_LShr(m_ConstantInt(CI), m_Value(X))) &&
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CI->getValue().isPowerOf2()) {
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unsigned CmpVal = CI->getValue().countTrailingZeros();
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return new ICmpInst(ICmpInst::ICMP_EQ, X,
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ConstantInt::get(X->getType(), CmpVal));
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}
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}
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break;
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case ICmpInst::ICMP_NE:
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}
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case ICmpInst::ICMP_NE: {
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if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max))
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return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
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// If all bits are known zero except for one, then we know at most one
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// bit is set. If the comparison is against zero, then this is a check
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// to see if *that* bit is set.
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APInt Op0KnownZeroInverted = ~Op0KnownZero;
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if (~Op1KnownZero == 0 && Op0KnownZeroInverted.isPowerOf2()) {
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// If the LHS is an AND with the same constant, look through it.
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Value *LHS = 0;
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ConstantInt *LHSC = 0;
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if (!match(Op0, m_And(m_Value(LHS), m_ConstantInt(LHSC))) ||
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LHSC->getValue() != Op0KnownZeroInverted)
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LHS = Op0;
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// If the LHS is 1 << x, and we know the result is a power of 2 like 8,
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// then turn "((1 << x)&8) != 0" into "x != 3".
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Value *X = 0;
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if (match(LHS, m_Shl(m_One(), m_Value(X)))) {
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unsigned CmpVal = Op0KnownZeroInverted.countTrailingZeros();
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return new ICmpInst(ICmpInst::ICMP_NE, X,
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ConstantInt::get(X->getType(), CmpVal));
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}
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// If the LHS is 8 >>u x, and we know the result is a power of 2 like 1,
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// then turn "((8 >>u x)&1) != 0" into "x != 3".
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ConstantInt *CI = 0;
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if (Op0KnownZeroInverted == 1 &&
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match(LHS, m_LShr(m_ConstantInt(CI), m_Value(X))) &&
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CI->getValue().isPowerOf2()) {
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unsigned CmpVal = CI->getValue().countTrailingZeros();
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return new ICmpInst(ICmpInst::ICMP_NE, X,
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ConstantInt::get(X->getType(), CmpVal));
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}
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}
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break;
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}
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case ICmpInst::ICMP_ULT:
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if (Op0Max.ult(Op1Min)) // A <u B -> true if max(A) < min(B)
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return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext()));
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@ -154,3 +154,41 @@ entry:
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; CHECK: @test16
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; CHECK: ret i1 undef
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}
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define i1 @test17(i32 %x) nounwind {
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%shl = shl i32 1, %x
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%and = and i32 %shl, 8
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%cmp = icmp eq i32 %and, 0
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ret i1 %cmp
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; CHECK: @test17
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; CHECK-NEXT: %cmp = icmp eq i32 %x, 3
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}
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define i1 @test18(i32 %x) nounwind {
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%sh = lshr i32 8, %x
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%and = and i32 %sh, 1
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%cmp = icmp eq i32 %and, 0
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ret i1 %cmp
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; CHECK: @test18
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; CHECK-NEXT: %cmp = icmp eq i32 %x, 3
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}
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define i1 @test19(i32 %x) nounwind {
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%shl = shl i32 1, %x
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%and = and i32 %shl, 8
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%cmp = icmp eq i32 %and, 8
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ret i1 %cmp
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; CHECK: @test19
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; CHECK-NEXT: %cmp = icmp ne i32 %x, 3
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}
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define i1 @test20(i32 %x) nounwind {
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%shl = shl i32 1, %x
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%and = and i32 %shl, 8
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%cmp = icmp ne i32 %and, 0
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ret i1 %cmp
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; CHECK: @test20
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; CHECK-NEXT: %cmp = icmp ne i32 %x, 3
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}
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