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authorEli Bendersky <eliben@google.com>2013-04-17 20:10:13 +0000
committerEli Bendersky <eliben@google.com>2013-04-17 20:10:13 +0000
commit50125482d399ae58223a7f39a1c001fdb635508a (patch)
tree85c69dff15af6c11300eb87b2b3ad0a7582437ed /lib
parent9c63f0d687cf1130ee2e76a6fdc87d71ae9d3961 (diff)
This patch teaches x86 fast-isel to generate the native div/idiv instructions
for the sdiv/srem/udiv/urem bitcode instructions. This is done for the i8, i16, and i32 types, as well as i64 for the x86_64 target. Patch by Jim Stichnoth git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179715 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib')
-rw-r--r--lib/Target/X86/X86FastISel.cpp125
1 files changed, 125 insertions, 0 deletions
diff --git a/lib/Target/X86/X86FastISel.cpp b/lib/Target/X86/X86FastISel.cpp
index cadec682a43..6884c92163b 100644
--- a/lib/Target/X86/X86FastISel.cpp
+++ b/lib/Target/X86/X86FastISel.cpp
@@ -107,6 +107,8 @@ private:
bool X86SelectShift(const Instruction *I);
+ bool X86SelectDivRem(const Instruction *I);
+
bool X86SelectSelect(const Instruction *I);
bool X86SelectTrunc(const Instruction *I);
@@ -1235,6 +1237,124 @@ bool X86FastISel::X86SelectShift(const Instruction *I) {
return true;
}
+bool X86FastISel::X86SelectDivRem(const Instruction *I) {
+ const static unsigned NumTypes = 4; // i8, i16, i32, i64
+ const static unsigned NumOps = 4; // SDiv, SRem, UDiv, URem
+ const static bool S = true; // IsSigned
+ const static bool U = false; // !IsSigned
+ const static unsigned Copy = TargetOpcode::COPY;
+ // For the X86 DIV/IDIV instruction, in most cases the dividend
+ // (numerator) must be in a specific register pair highreg:lowreg,
+ // producing the quotient in lowreg and the remainder in highreg.
+ // For most data types, to set up the instruction, the dividend is
+ // copied into lowreg, and lowreg is sign-extended or zero-extended
+ // into highreg. The exception is i8, where the dividend is defined
+ // as a single register rather than a register pair, and we
+ // therefore directly sign-extend or zero-extend the dividend into
+ // lowreg, instead of copying, and ignore the highreg.
+ const static struct DivRemEntry {
+ // The following portion depends only on the data type.
+ const TargetRegisterClass *RC;
+ unsigned LowInReg; // low part of the register pair
+ unsigned HighInReg; // high part of the register pair
+ // The following portion depends on both the data type and the operation.
+ struct DivRemResult {
+ unsigned OpDivRem; // The specific DIV/IDIV opcode to use.
+ unsigned OpSignExtend; // Opcode for sign-extending lowreg into
+ // highreg, or copying a zero into highreg.
+ unsigned OpCopy; // Opcode for copying dividend into lowreg, or
+ // zero/sign-extending into lowreg for i8.
+ unsigned DivRemResultReg; // Register containing the desired result.
+ bool IsOpSigned; // Whether to use signed or unsigned form.
+ } ResultTable[NumOps];
+ } OpTable[NumTypes] = {
+ { &X86::GR8RegClass, X86::AX, 0, {
+ { X86::IDIV8r, 0, X86::MOVSX16rr8, X86::AL, S }, // SDiv
+ { X86::IDIV8r, 0, X86::MOVSX16rr8, X86::AH, S }, // SRem
+ { X86::DIV8r, 0, X86::MOVZX16rr8, X86::AL, U }, // UDiv
+ { X86::DIV8r, 0, X86::MOVZX16rr8, X86::AH, U }, // URem
+ }
+ }, // i8
+ { &X86::GR16RegClass, X86::AX, X86::DX, {
+ { X86::IDIV16r, X86::CWD, Copy, X86::AX, S }, // SDiv
+ { X86::IDIV16r, X86::CWD, Copy, X86::DX, S }, // SRem
+ { X86::DIV16r, X86::MOV16r0, Copy, X86::AX, U }, // UDiv
+ { X86::DIV16r, X86::MOV16r0, Copy, X86::DX, U }, // URem
+ }
+ }, // i16
+ { &X86::GR32RegClass, X86::EAX, X86::EDX, {
+ { X86::IDIV32r, X86::CDQ, Copy, X86::EAX, S }, // SDiv
+ { X86::IDIV32r, X86::CDQ, Copy, X86::EDX, S }, // SRem
+ { X86::DIV32r, X86::MOV32r0, Copy, X86::EAX, U }, // UDiv
+ { X86::DIV32r, X86::MOV32r0, Copy, X86::EDX, U }, // URem
+ }
+ }, // i32
+ { &X86::GR64RegClass, X86::RAX, X86::RDX, {
+ { X86::IDIV64r, X86::CQO, Copy, X86::RAX, S }, // SDiv
+ { X86::IDIV64r, X86::CQO, Copy, X86::RDX, S }, // SRem
+ { X86::DIV64r, X86::MOV64r0, Copy, X86::RAX, U }, // UDiv
+ { X86::DIV64r, X86::MOV64r0, Copy, X86::RDX, U }, // URem
+ }
+ }, // i64
+ };
+
+ MVT VT;
+ if (!isTypeLegal(I->getType(), VT))
+ return false;
+
+ unsigned TypeIndex, OpIndex;
+ switch (VT.SimpleTy) {
+ default: return false;
+ case MVT::i8: TypeIndex = 0; break;
+ case MVT::i16: TypeIndex = 1; break;
+ case MVT::i32: TypeIndex = 2; break;
+ case MVT::i64: TypeIndex = 3;
+ if (!Subtarget->is64Bit())
+ return false;
+ break;
+ }
+
+ switch (I->getOpcode()) {
+ default: llvm_unreachable("Unexpected div/rem opcode");
+ case Instruction::SDiv: OpIndex = 0; break;
+ case Instruction::SRem: OpIndex = 1; break;
+ case Instruction::UDiv: OpIndex = 2; break;
+ case Instruction::URem: OpIndex = 3; break;
+ }
+
+ const DivRemEntry &TypeEntry = OpTable[TypeIndex];
+ const DivRemEntry::DivRemResult &OpEntry = TypeEntry.ResultTable[OpIndex];
+ unsigned Op0Reg = getRegForValue(I->getOperand(0));
+ if (Op0Reg == 0)
+ return false;
+ unsigned Op1Reg = getRegForValue(I->getOperand(1));
+ if (Op1Reg == 0)
+ return false;
+
+ // Move op0 into low-order input register.
+ BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
+ TII.get(OpEntry.OpCopy), TypeEntry.LowInReg).addReg(Op0Reg);
+ // Zero-extend or sign-extend into high-order input register.
+ if (OpEntry.OpSignExtend) {
+ if (OpEntry.IsOpSigned)
+ BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
+ TII.get(OpEntry.OpSignExtend));
+ else
+ BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
+ TII.get(OpEntry.OpSignExtend), TypeEntry.HighInReg);
+ }
+ // Generate the DIV/IDIV instruction.
+ BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
+ TII.get(OpEntry.OpDivRem)).addReg(Op1Reg);
+ // Copy output register into result register.
+ unsigned ResultReg = createResultReg(TypeEntry.RC);
+ BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
+ TII.get(Copy), ResultReg).addReg(OpEntry.DivRemResultReg);
+ UpdateValueMap(I, ResultReg);
+
+ return true;
+}
+
bool X86FastISel::X86SelectSelect(const Instruction *I) {
MVT VT;
if (!isTypeLegal(I->getType(), VT))
@@ -2084,6 +2204,11 @@ X86FastISel::TargetSelectInstruction(const Instruction *I) {
case Instruction::AShr:
case Instruction::Shl:
return X86SelectShift(I);
+ case Instruction::SDiv:
+ case Instruction::UDiv:
+ case Instruction::SRem:
+ case Instruction::URem:
+ return X86SelectDivRem(I);
case Instruction::Select:
return X86SelectSelect(I);
case Instruction::Trunc: