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authorMatt Arsenault <Matthew.Arsenault@amd.com>2013-10-29 20:59:29 +0000
committerMatt Arsenault <Matthew.Arsenault@amd.com>2013-10-29 20:59:29 +0000
commit2b0002b579dba5604a2673bbee2cd9969e183a71 (patch)
tree6a0a29807f6406e8efcda11a24e0eeada14d292d /include
parent5203b7773e29b36e38aac0ce9358fa7843065681 (diff)
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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
Diffstat (limited to 'include')
-rw-r--r--include/llvm/Target/TargetLowering.h28
1 files changed, 13 insertions, 15 deletions
diff --git a/include/llvm/Target/TargetLowering.h b/include/llvm/Target/TargetLowering.h
index 3cde173..5b9e377 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;