SDValue(CurDAG->getMachineNode(Opc, dl, MVT::Flag, N1, InFlag), 0);
}
+ // Prevent use of AH in a REX instruction by referencing AX instead.
+ if (HiReg == X86::AH && Subtarget->is64Bit() &&
+ !SDValue(Node, 1).use_empty()) {
+ SDValue Result = CurDAG->getCopyFromReg(CurDAG->getEntryNode(), dl,
+ X86::AX, MVT::i16, InFlag);
+ InFlag = Result.getValue(2);
+ // Get the low part if needed. Don't use getCopyFromReg for aliasing
+ // registers.
+ if (!SDValue(Node, 0).use_empty())
+ ReplaceUses(SDValue(Node, 1),
+ CurDAG->getTargetExtractSubreg(X86::sub_8bit, dl, MVT::i8, Result));
+
+ // Shift AX down 8 bits.
+ Result = SDValue(CurDAG->getMachineNode(X86::SHR16ri, dl, MVT::i16,
+ Result,
+ CurDAG->getTargetConstant(8, MVT::i8)), 0);
+ // Then truncate it down to i8.
+ ReplaceUses(SDValue(Node, 1),
+ CurDAG->getTargetExtractSubreg(X86::sub_8bit, dl, MVT::i8, Result));
+ }
// Copy the low half of the result, if it is needed.
if (!SDValue(Node, 0).use_empty()) {
SDValue Result = CurDAG->getCopyFromReg(CurDAG->getEntryNode(), dl,
}
// Copy the high half of the result, if it is needed.
if (!SDValue(Node, 1).use_empty()) {
- SDValue Result;
- if (HiReg == X86::AH && Subtarget->is64Bit()) {
- // Prevent use of AH in a REX instruction by referencing AX instead.
- // Shift it down 8 bits.
- Result = CurDAG->getCopyFromReg(CurDAG->getEntryNode(), dl,
- X86::AX, MVT::i16, InFlag);
- InFlag = Result.getValue(2);
- Result = SDValue(CurDAG->getMachineNode(X86::SHR16ri, dl, MVT::i16,
- Result,
- CurDAG->getTargetConstant(8, MVT::i8)), 0);
- // Then truncate it down to i8.
- Result = CurDAG->getTargetExtractSubreg(X86::sub_8bit, dl,
- MVT::i8, Result);
- } else {
- Result = CurDAG->getCopyFromReg(CurDAG->getEntryNode(), dl,
- HiReg, NVT, InFlag);
- InFlag = Result.getValue(2);
- }
+ SDValue Result = CurDAG->getCopyFromReg(CurDAG->getEntryNode(), dl,
+ HiReg, NVT, InFlag);
+ InFlag = Result.getValue(2);
ReplaceUses(SDValue(Node, 1), Result);
DEBUG(dbgs() << "=> "; Result.getNode()->dump(CurDAG); dbgs() << '\n');
}
SDValue(CurDAG->getMachineNode(Opc, dl, MVT::Flag, N1, InFlag), 0);
}
+ // Prevent use of AH in a REX instruction by referencing AX instead.
+ // Shift it down 8 bits.
+ if (HiReg == X86::AH && Subtarget->is64Bit() &&
+ !SDValue(Node, 1).use_empty()) {
+ SDValue Result = CurDAG->getCopyFromReg(CurDAG->getEntryNode(), dl,
+ X86::AX, MVT::i16, InFlag);
+ InFlag = Result.getValue(2);
+
+ // If we also need AL (the quotient), get it by extracting a subreg from
+ // Result. The fast register allocator does not like multiple CopyFromReg
+ // nodes using aliasing registers.
+ if (!SDValue(Node, 0).use_empty())
+ ReplaceUses(SDValue(Node, 0),
+ CurDAG->getTargetExtractSubreg(X86::sub_8bit, dl, MVT::i8, Result));
+
+ // Shift AX right by 8 bits instead of using AH.
+ Result = SDValue(CurDAG->getMachineNode(X86::SHR16ri, dl, MVT::i16,
+ Result,
+ CurDAG->getTargetConstant(8, MVT::i8)),
+ 0);
+ ReplaceUses(SDValue(Node, 1),
+ CurDAG->getTargetExtractSubreg(X86::sub_8bit, dl, MVT::i8, Result));
+ }
// Copy the division (low) result, if it is needed.
if (!SDValue(Node, 0).use_empty()) {
SDValue Result = CurDAG->getCopyFromReg(CurDAG->getEntryNode(), dl,
}
// Copy the remainder (high) result, if it is needed.
if (!SDValue(Node, 1).use_empty()) {
- SDValue Result;
- if (HiReg == X86::AH && Subtarget->is64Bit()) {
- // Prevent use of AH in a REX instruction by referencing AX instead.
- // Shift it down 8 bits.
- Result = CurDAG->getCopyFromReg(CurDAG->getEntryNode(), dl,
- X86::AX, MVT::i16, InFlag);
- InFlag = Result.getValue(2);
- Result = SDValue(CurDAG->getMachineNode(X86::SHR16ri, dl, MVT::i16,
- Result,
- CurDAG->getTargetConstant(8, MVT::i8)),
- 0);
- // Then truncate it down to i8.
- Result = CurDAG->getTargetExtractSubreg(X86::sub_8bit, dl,
- MVT::i8, Result);
- } else {
- Result = CurDAG->getCopyFromReg(CurDAG->getEntryNode(), dl,
- HiReg, NVT, InFlag);
- InFlag = Result.getValue(2);
- }
+ SDValue Result = CurDAG->getCopyFromReg(CurDAG->getEntryNode(), dl,
+ HiReg, NVT, InFlag);
+ InFlag = Result.getValue(2);
ReplaceUses(SDValue(Node, 1), Result);
DEBUG(dbgs() << "=> "; Result.getNode()->dump(CurDAG); dbgs() << '\n');
}
--- /dev/null
+; RUN: llc -O0 -relocation-model=pic -disable-fp-elim < %s
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+target triple = "x86_64-apple-darwin10"
+
+; This file contains functions that may crash llc -O0
+
+; The DIV8 instruction produces results in AH and AL, but we don't want to use
+; AH in 64-bit mode. The hack used must not generate copyFromReg nodes for
+; aliased registers (AX and AL) - RegAllocFast does not like that.
+; PR7312
+define i32 @div8() nounwind {
+entry:
+ %0 = trunc i64 undef to i8 ; <i8> [#uses=3]
+ %1 = udiv i8 0, %0 ; <i8> [#uses=1]
+ %2 = urem i8 0, %0 ; <i8> [#uses=1]
+ %3 = icmp uge i8 %2, %0 ; <i1> [#uses=1]
+ br i1 %3, label %"40", label %"39"
+
+"39": ; preds = %"36"
+ %4 = zext i8 %1 to i32 ; <i32> [#uses=1]
+ %5 = mul nsw i32 %4, undef ; <i32> [#uses=1]
+ %6 = add nsw i32 %5, undef ; <i32> [#uses=1]
+ %7 = icmp ne i32 %6, undef ; <i1> [#uses=1]
+ br i1 %7, label %"40", label %"41"
+
+"40": ; preds = %"39", %"36"
+ unreachable
+
+"41": ; preds = %"39"
+ unreachable
+}