Finally implement correct ordered comparisons for PPC, even though
the code generated is not wonderful. This turns a miscompilation into
a code quality bug (noted in the ppc readme). This fixes PR642, which
is over 2 years old (!). Nate, please review this.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@45742 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/PowerPC/PPCISelDAGToDAG.cpp b/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
index 6e8cebd..df1d9b5 100644
--- a/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
+++ b/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
@@ -624,29 +624,34 @@
/// getCRIdxForSetCC - Return the index of the condition register field
/// associated with the SetCC condition, and whether or not the field is
/// treated as inverted. That is, lt = 0; ge = 0 inverted.
-static unsigned getCRIdxForSetCC(ISD::CondCode CC, bool& Inv) {
+///
+/// If this returns with Other != -1, then the returned comparison is an or of
+/// two simpler comparisons. In this case, Invert is guaranteed to be false.
+static unsigned getCRIdxForSetCC(ISD::CondCode CC, bool &Invert, int &Other) {
+ Invert = false;
+ Other = -1;
switch (CC) {
default: assert(0 && "Unknown condition!"); abort();
- case ISD::SETOLT: // FIXME: This is incorrect see PR642.
- case ISD::SETULT:
- case ISD::SETLT: Inv = false; return 0;
- case ISD::SETOGE: // FIXME: This is incorrect see PR642.
+ case ISD::SETOLT:
+ case ISD::SETLT: return 0; // Bit #0 = SETOLT
+ case ISD::SETOGT:
+ case ISD::SETGT: return 1; // Bit #1 = SETOGT
+ case ISD::SETOEQ:
+ case ISD::SETEQ: return 2; // Bit #2 = SETOEQ
+ case ISD::SETUO: return 3; // Bit #3 = SETUO
case ISD::SETUGE:
- case ISD::SETGE: Inv = true; return 0;
- case ISD::SETOGT: // FIXME: This is incorrect see PR642.
- case ISD::SETUGT:
- case ISD::SETGT: Inv = false; return 1;
- case ISD::SETOLE: // FIXME: This is incorrect see PR642.
+ case ISD::SETGE: Invert = true; return 0; // !Bit #0 = SETUGE
case ISD::SETULE:
- case ISD::SETLE: Inv = true; return 1;
- case ISD::SETOEQ: // FIXME: This is incorrect see PR642.
- case ISD::SETUEQ:
- case ISD::SETEQ: Inv = false; return 2;
- case ISD::SETONE: // FIXME: This is incorrect see PR642.
+ case ISD::SETLE: Invert = true; return 1; // !Bit #1 = SETULE
case ISD::SETUNE:
- case ISD::SETNE: Inv = true; return 2;
- case ISD::SETO: Inv = true; return 3;
- case ISD::SETUO: Inv = false; return 3;
+ case ISD::SETNE: Invert = true; return 2; // !Bit #2 = SETUNE
+ case ISD::SETO: Invert = true; return 3; // !Bit #3 = SETO
+ case ISD::SETULT: Other = 0; return 3; // SETOLT | SETUO
+ case ISD::SETUGT: Other = 1; return 3; // SETOGT | SETUO
+ case ISD::SETUEQ: Other = 2; return 3; // SETOEQ | SETUO
+ case ISD::SETOGE: Other = 1; return 2; // SETOGT | SETOEQ
+ case ISD::SETOLE: Other = 0; return 2; // SETOLT | SETOEQ
+ case ISD::SETONE: Other = 0; return 1; // SETOLT | SETOGT
}
return 0;
}
@@ -726,7 +731,8 @@
}
bool Inv;
- unsigned Idx = getCRIdxForSetCC(CC, Inv);
+ int OtherCondIdx;
+ unsigned Idx = getCRIdxForSetCC(CC, Inv, OtherCondIdx);
SDOperand CCReg = SelectCC(N->getOperand(0), N->getOperand(1), CC);
SDOperand IntCR;
@@ -737,7 +743,7 @@
CCReg = CurDAG->getCopyToReg(CurDAG->getEntryNode(), CR7Reg, CCReg,
InFlag).getValue(1);
- if (PPCSubTarget.isGigaProcessor())
+ if (PPCSubTarget.isGigaProcessor() && OtherCondIdx == -1)
IntCR = SDOperand(CurDAG->getTargetNode(PPC::MFOCRF, MVT::i32, CR7Reg,
CCReg), 0);
else
@@ -745,13 +751,26 @@
SDOperand Ops[] = { IntCR, getI32Imm((32-(3-Idx)) & 31),
getI32Imm(31), getI32Imm(31) };
- if (!Inv) {
+ if (OtherCondIdx == -1 && !Inv)
return CurDAG->SelectNodeTo(N, PPC::RLWINM, MVT::i32, Ops, 4);
- } else {
- SDOperand Tmp =
- SDOperand(CurDAG->getTargetNode(PPC::RLWINM, MVT::i32, Ops, 4), 0);
+
+ // Get the specified bit.
+ SDOperand Tmp =
+ SDOperand(CurDAG->getTargetNode(PPC::RLWINM, MVT::i32, Ops, 4), 0);
+ if (Inv) {
+ assert(OtherCondIdx == -1 && "Can't have split plus negation");
return CurDAG->SelectNodeTo(N, PPC::XORI, MVT::i32, Tmp, getI32Imm(1));
}
+
+ // Otherwise, we have to turn an operation like SETONE -> SETOLT | SETOGT.
+ // We already got the bit for the first part of the comparison (e.g. SETULE).
+
+ // Get the other bit of the comparison.
+ Ops[1] = getI32Imm((32-(3-OtherCondIdx)) & 31);
+ SDOperand OtherCond =
+ SDOperand(CurDAG->getTargetNode(PPC::RLWINM, MVT::i32, Ops, 4), 0);
+
+ return CurDAG->SelectNodeTo(N, PPC::OR, MVT::i32, Tmp, OtherCond);
}