From 2b0002b579dba5604a2673bbee2cd9969e183a71 Mon Sep 17 00:00:00 2001 From: Matt Arsenault Date: Tue, 29 Oct 2013 20:59:29 +0000 Subject: [PATCH] Workaround MSVC 32-bit miscompile of getCondCodeAction. Use 32-bit types for the array instead of 64. This should generally be better anyway. In optimized + assert builds, I saw a failure when a cond code / type combination that is never set was loading a non-zero value and hitting the != Promote assert. It turns out when loading the 64-bit value to do the shift, the assembly loads the 2 32-bit halves from non-consecutive addresses. The address the second half of the loaded uint64_t doesn't include the offset of the array in the struct. Instead of being offset + 4, it's just + 4. I'm not entirely sure why this wasn't observed before. setCondCodeAction isn't heavily used by the in-tree targets, and not with the higher valued vector SimpleValueTypes. Only PPC is using one of the > 32 valued types, and that is probably never used by anyone on a 32-bit MSVC compiled host. I ran into this when upgrading LLVM versions, so I guess the value loaded from the nonsense address happened to work out before. No test since I'm not really sure if / how it can be reproduced with the current in tree targets, and it's not supposed to change anything. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193650 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/Target/TargetLowering.h | 28 +++++++++++++--------------- 1 file changed, 13 insertions(+), 15 deletions(-) diff --git a/include/llvm/Target/TargetLowering.h b/include/llvm/Target/TargetLowering.h index 3cde173dfdb..5b9e3774591 100644 --- a/include/llvm/Target/TargetLowering.h +++ b/include/llvm/Target/TargetLowering.h @@ -520,13 +520,12 @@ public: LegalizeAction getCondCodeAction(ISD::CondCode CC, MVT VT) const { assert((unsigned)CC < array_lengthof(CondCodeActions) && - (unsigned)VT.SimpleTy < sizeof(CondCodeActions[0])*4 && + ((unsigned)VT.SimpleTy >> 4) < array_lengthof(CondCodeActions[0]) && "Table isn't big enough!"); - /// The lower 5 bits of the SimpleTy index into Nth 2bit set from the 64bit - /// value and the upper 27 bits index into the second dimension of the - /// array to select what 64bit value to use. - LegalizeAction Action = (LegalizeAction) - ((CondCodeActions[CC][VT.SimpleTy >> 5] >> (2*(VT.SimpleTy & 0x1F))) & 3); + // See setCondCodeAction for how this is encoded. + uint32_t Shift = 2 * (VT.SimpleTy & 0xF); + uint32_t Value = CondCodeActions[CC][VT.SimpleTy >> 4]; + LegalizeAction Action = (LegalizeAction) ((Value >> Shift) & 0x3); assert(Action != Promote && "Can't promote condition code!"); return Action; } @@ -1020,13 +1019,12 @@ protected: assert(VT < MVT::LAST_VALUETYPE && (unsigned)CC < array_lengthof(CondCodeActions) && "Table isn't big enough!"); - /// The lower 5 bits of the SimpleTy index into Nth 2bit set from the 64bit - /// value and the upper 27 bits index into the second dimension of the - /// array to select what 64bit value to use. - CondCodeActions[(unsigned)CC][VT.SimpleTy >> 5] - &= ~(uint64_t(3UL) << (VT.SimpleTy & 0x1F)*2); - CondCodeActions[(unsigned)CC][VT.SimpleTy >> 5] - |= (uint64_t)Action << (VT.SimpleTy & 0x1F)*2; + /// The lower 5 bits of the SimpleTy index into Nth 2bit set from the 32-bit + /// value and the upper 27 bits index into the second dimension of the array + /// to select what 32-bit value to use. + uint32_t Shift = 2 * (VT.SimpleTy & 0xF); + CondCodeActions[CC][VT.SimpleTy >> 4] &= ~((uint32_t)0x3 << Shift); + CondCodeActions[CC][VT.SimpleTy >> 4] |= (uint32_t)Action << Shift; } /// If Opc/OrigVT is specified as being promoted, the promotion code defaults @@ -1448,8 +1446,8 @@ private: /// /// Because each CC action takes up 2 bits, we need to have the array size be /// large enough to fit all of the value types. This can be done by dividing - /// the MVT::LAST_VALUETYPE by 32 and adding one. - uint64_t CondCodeActions[ISD::SETCC_INVALID][(MVT::LAST_VALUETYPE / 32) + 1]; + /// the MVT::LAST_VALUETYPE by 16 and adding one. + uint32_t CondCodeActions[ISD::SETCC_INVALID][(MVT::LAST_VALUETYPE + 15) / 16]; ValueTypeActionImpl ValueTypeActions; -- 2.50.0