Author: hans Date: Thu Feb 2 16:19:34 2017 New Revision: 293947 URL: http://llvm.org/viewvc/llvm-project?rev=293947&view=rev Log: Merging r293345: ------------------------------------------------------------------------ r293345 | spatel | 2017-01-27 15:26:27 -0800 (Fri, 27 Jan 2017) | 19 lines
[InstCombine] move icmp transforms that might be recognized as min/max and inf-loop (PR31751) This is a minimal patch to avoid the infinite loop in: https://llvm.org/bugs/show_bug.cgi?id=31751 But the general problem is bigger: we're not canonicalizing all of the min/max forms reported by value tracking's matchSelectPattern(), and we don't define min/max consistently. Some code uses matchSelectPattern(), other code uses matchers like m_Umax, and others have their own inline definitions which may be subtly different from any of the above. The reason that the test cases in this patch need a cast op to trigger is because we don't (yet) canonicalize all min/max forms based on matchSelectPattern() in canonicalizeMinMaxWithConstant(), but we do make min/max+cast transforms based on matchSelectPattern() in visitSelectInst(). The location of the icmp transforms that trigger the inf-loop seems arbitrary at best, so I'm moving those behind the min/max fence in visitICmpInst() as the quick fix. ------------------------------------------------------------------------ Modified: llvm/branches/release_40/ (props changed) llvm/branches/release_40/lib/Transforms/InstCombine/InstCombineCompares.cpp llvm/branches/release_40/test/Transforms/InstCombine/minmax-fold.ll Propchange: llvm/branches/release_40/ ------------------------------------------------------------------------------ --- svn:mergeinfo (original) +++ svn:mergeinfo Thu Feb 2 16:19:34 2017 @@ -1,3 +1,3 @@ /llvm/branches/Apple/Pertwee:110850,110961 /llvm/branches/type-system-rewrite:133420-134817 -/llvm/trunk:155241,291858-291859,291863,291875,291909,291918,291966,291968,291979,292117,292133,292167,292169-292170,292242,292254-292255,292280,292323,292444,292467,292516,292583,292624-292625,292641,292651,292667,292711-292713,292758,293021,293025,293230,293259,293291,293293,293309,293417,293522,293542,293629,293635,293658,293673,293727,293730 +/llvm/trunk:155241,291858-291859,291863,291875,291909,291918,291966,291968,291979,292117,292133,292167,292169-292170,292242,292254-292255,292280,292323,292444,292467,292516,292583,292624-292625,292641,292651,292667,292711-292713,292758,293021,293025,293230,293259,293291,293293,293309,293345,293417,293522,293542,293629,293635,293658,293673,293727,293730 Modified: llvm/branches/release_40/lib/Transforms/InstCombine/InstCombineCompares.cpp URL: http://llvm.org/viewvc/llvm-project/llvm/branches/release_40/lib/Transforms/InstCombine/InstCombineCompares.cpp?rev=293947&r1=293946&r2=293947&view=diff ============================================================================== --- llvm/branches/release_40/lib/Transforms/InstCombine/InstCombineCompares.cpp (original) +++ llvm/branches/release_40/lib/Transforms/InstCombine/InstCombineCompares.cpp Thu Feb 2 16:19:34 2017 @@ -4039,11 +4039,6 @@ Instruction *InstCombiner::foldICmpUsing Constant *CMinus1 = ConstantInt::get(Op0->getType(), *CmpC - 1); return new ICmpInst(ICmpInst::ICMP_EQ, Op0, CMinus1); } - // (x <u 2147483648) -> (x >s -1) -> true if sign bit clear - if (CmpC->isMinSignedValue()) { - Constant *AllOnes = Constant::getAllOnesValue(Op0->getType()); - return new ICmpInst(ICmpInst::ICMP_SGT, Op0, AllOnes); - } } break; } @@ -4063,11 +4058,6 @@ Instruction *InstCombiner::foldICmpUsing if (*CmpC == Op0Max - 1) return new ICmpInst(ICmpInst::ICMP_EQ, Op0, ConstantInt::get(Op1->getType(), *CmpC + 1)); - - // (x >u 2147483647) -> (x <s 0) -> true if sign bit set - if (CmpC->isMaxSignedValue()) - return new ICmpInst(ICmpInst::ICMP_SLT, Op0, - Constant::getNullValue(Op0->getType())); } break; } @@ -4299,6 +4289,27 @@ Instruction *InstCombiner::visitICmpInst (SI->getOperand(2) == Op0 && SI->getOperand(1) == Op1)) return nullptr; + // FIXME: We only do this after checking for min/max to prevent infinite + // looping caused by a reverse canonicalization of these patterns for min/max. + // FIXME: The organization of folds is a mess. These would naturally go into + // canonicalizeCmpWithConstant(), but we can't move all of the above folds + // down here after the min/max restriction. + ICmpInst::Predicate Pred = I.getPredicate(); + const APInt *C; + if (match(Op1, m_APInt(C))) { + // For i32: x >u 2147483647 -> x <s 0 -> true if sign bit set + if (Pred == ICmpInst::ICMP_UGT && C->isMaxSignedValue()) { + Constant *Zero = Constant::getNullValue(Op0->getType()); + return new ICmpInst(ICmpInst::ICMP_SLT, Op0, Zero); + } + + // For i32: x <u 2147483648 -> x >s -1 -> true if sign bit clear + if (Pred == ICmpInst::ICMP_ULT && C->isMinSignedValue()) { + Constant *AllOnes = Constant::getAllOnesValue(Op0->getType()); + return new ICmpInst(ICmpInst::ICMP_SGT, Op0, AllOnes); + } + } + if (Instruction *Res = foldICmpInstWithConstant(I)) return Res; Modified: llvm/branches/release_40/test/Transforms/InstCombine/minmax-fold.ll URL: http://llvm.org/viewvc/llvm-project/llvm/branches/release_40/test/Transforms/InstCombine/minmax-fold.ll?rev=293947&r1=293946&r2=293947&view=diff ============================================================================== --- llvm/branches/release_40/test/Transforms/InstCombine/minmax-fold.ll (original) +++ llvm/branches/release_40/test/Transforms/InstCombine/minmax-fold.ll Thu Feb 2 16:19:34 2017 @@ -339,3 +339,84 @@ define i32 @test75(i32 %x) { ret i32 %retval } +; The next 3 min tests should canonicalize to the same form...and not infinite loop. + +define double @PR31751_umin1(i32 %x) { +; CHECK-LABEL: @PR31751_umin1( +; CHECK-NEXT: [[TMP1:%.*]] = icmp ult i32 %x, 2147483647 +; CHECK-NEXT: [[CONV1:%.*]] = select i1 [[TMP1]], i32 %x, i32 2147483647 +; CHECK-NEXT: [[TMP2:%.*]] = sitofp i32 [[CONV1]] to double +; CHECK-NEXT: ret double [[TMP2]] +; + %cmp = icmp slt i32 %x, 0 + %sel = select i1 %cmp, i32 2147483647, i32 %x + %conv = sitofp i32 %sel to double + ret double %conv +} + +define double @PR31751_umin2(i32 %x) { +; CHECK-LABEL: @PR31751_umin2( +; CHECK-NEXT: [[CMP:%.*]] = icmp ult i32 %x, 2147483647 +; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i32 %x, i32 2147483647 +; CHECK-NEXT: [[CONV:%.*]] = sitofp i32 [[SEL]] to double +; CHECK-NEXT: ret double [[CONV]] +; + %cmp = icmp ult i32 %x, 2147483647 + %sel = select i1 %cmp, i32 %x, i32 2147483647 + %conv = sitofp i32 %sel to double + ret double %conv +} + +define double @PR31751_umin3(i32 %x) { +; CHECK-LABEL: @PR31751_umin3( +; CHECK-NEXT: [[TMP1:%.*]] = icmp ult i32 %x, 2147483647 +; CHECK-NEXT: [[SEL:%.*]] = select i1 [[TMP1]], i32 %x, i32 2147483647 +; CHECK-NEXT: [[CONV:%.*]] = sitofp i32 [[SEL]] to double +; CHECK-NEXT: ret double [[CONV]] +; + %cmp = icmp ugt i32 %x, 2147483647 + %sel = select i1 %cmp, i32 2147483647, i32 %x + %conv = sitofp i32 %sel to double + ret double %conv +} + +; The next 3 max tests should canonicalize to the same form...and not infinite loop. + +define double @PR31751_umax1(i32 %x) { +; CHECK-LABEL: @PR31751_umax1( +; CHECK-NEXT: [[TMP1:%.*]] = icmp ugt i32 %x, -2147483648 +; CHECK-NEXT: [[CONV1:%.*]] = select i1 [[TMP1]], i32 %x, i32 -2147483648 +; CHECK-NEXT: [[TMP2:%.*]] = sitofp i32 [[CONV1]] to double +; CHECK-NEXT: ret double [[TMP2]] +; + %cmp = icmp sgt i32 %x, -1 + %sel = select i1 %cmp, i32 2147483648, i32 %x + %conv = sitofp i32 %sel to double + ret double %conv +} + +define double @PR31751_umax2(i32 %x) { +; CHECK-LABEL: @PR31751_umax2( +; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i32 %x, -2147483648 +; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i32 %x, i32 -2147483648 +; CHECK-NEXT: [[CONV:%.*]] = sitofp i32 [[SEL]] to double +; CHECK-NEXT: ret double [[CONV]] +; + %cmp = icmp ugt i32 %x, 2147483648 + %sel = select i1 %cmp, i32 %x, i32 2147483648 + %conv = sitofp i32 %sel to double + ret double %conv +} + +define double @PR31751_umax3(i32 %x) { +; CHECK-LABEL: @PR31751_umax3( +; CHECK-NEXT: [[TMP1:%.*]] = icmp ugt i32 %x, -2147483648 +; CHECK-NEXT: [[SEL:%.*]] = select i1 [[TMP1]], i32 %x, i32 -2147483648 +; CHECK-NEXT: [[CONV:%.*]] = sitofp i32 [[SEL]] to double +; CHECK-NEXT: ret double [[CONV]] +; + %cmp = icmp ult i32 %x, 2147483648 + %sel = select i1 %cmp, i32 2147483648, i32 %x + %conv = sitofp i32 %sel to double + ret double %conv +} _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
