From 76c94b616924b19b850e274df0c6485b9395fcb9 Mon Sep 17 00:00:00 2001 From: Reid Spencer Date: Tue, 15 May 2007 02:26:52 +0000 Subject: [PATCH] Un-brain-dead-ify the lowering of part set for the reverse case. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37071 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/IntrinsicLowering.cpp | 164 +++++++++++++----------------- 1 file changed, 69 insertions(+), 95 deletions(-) diff --git a/lib/CodeGen/IntrinsicLowering.cpp b/lib/CodeGen/IntrinsicLowering.cpp index c590c1ed4d7..b870545008a 100644 --- a/lib/CodeGen/IntrinsicLowering.cpp +++ b/lib/CodeGen/IntrinsicLowering.cpp @@ -442,57 +442,6 @@ static Instruction *LowerPartSet(CallInst *CI) { // If we haven't defined the impl function yet, do so now if (F->isDeclaration()) { - // Note: the following code is based on code generated by llvm2cpp with - // the following input. This is just *one* example of a generated function. - // The functions vary by bit width of result and first two arguments. - // The generated code has been changed to deal with any bit width not just - // the 32/64 bitwidths used in the above sample. - // - // define i64 @part_set(i64 %Val, i32 %Rep, i32 %Lo, i32 %Hi) { - // entry: - // %is_forward = icmp ult i32 %Lo, %Hi - // %Lo.pn = select i1 %is_forward, i32 %Hi, i32 %Lo - // %Hi.pn = select i1 %is_forward, i32 %Lo, i32 %Hi - // %iftmp.16.0 = sub i32 %Lo.pn, %Hi.pn - // icmp ult i32 %iftmp.16.0, 32 - // br i1 %1, label %cond_true11, label %cond_next19 - // cond_true11: - // %tmp13 = sub i32 32, %iftmp.16.0 - // %tmp14 = lshr i32 -1, %tmp13 - // %tmp16 = and i32 %tmp14, %Rep - // br label %cond_next19 - // cond_next19: - // %iftmp.17.0 = phi i32 [ %tmp16, %cond_true11 ], [ %Rep, %entry ] - // %tmp2021 = zext i32 %iftmp.17.0 to i64 - // icmp ugt i32 %Lo, %Hi - // br i1 %2, label %cond_next60, label %cond_true24 - // cond_true24: - // %tmp25.cast = zext i32 %Hi to i64 - // %tmp26 = lshr i64 -1, %tmp25.cast - // %tmp27.cast = zext i32 %Lo to i64 - // %tmp28 = shl i64 %tmp26, %tmp27.cast - // %tmp28not = xor i64 %tmp28, -1 - // %tmp31 = shl i64 %tmp2021, %tmp27.cast - // %tmp34 = and i64 %tmp28not, %Val - // %Val_addr.064 = or i64 %tmp31, %tmp34 - // ret i64 %Val_addr.064 - // cond_next60: - // %tmp39.cast = zext i32 %Lo to i64 - // %tmp40 = shl i64 -1, %tmp39.cast - // %tmp41.cast = zext i32 %Hi to i64 - // %tmp42 = shl i64 -1, %tmp41.cast - // %tmp45.demorgan = or i64 %tmp42, %tmp40 - // %tmp45 = xor i64 %tmp45.demorgan, -1 - // %tmp47 = and i64 %tmp45, %Val - // %tmp50 = shl i64 %tmp2021, %tmp39.cast - // %tmp52 = sub i32 32, %Hi - // %tmp52.cast = zext i32 %tmp52 to i64 - // %tmp54 = lshr i64 %tmp2021, %tmp52.cast - // %tmp57 = or i64 %tmp50, %tmp47 - // %Val_addr.0 = or i64 %tmp57, %tmp54 - // ret i64 %Val_addr.0 - // } - // Get the arguments for the function. Function::arg_iterator args = F->arg_begin(); Value* Val = args++; Val->setName("Val"); @@ -510,27 +459,31 @@ static Instruction *LowerPartSet(CallInst *CI) { ConstantInt* RepBitWidth = ConstantInt::get(Type::Int32Ty, RepBits); ConstantInt* RepMask = ConstantInt::getAllOnesValue(RepTy); ConstantInt* ValMask = ConstantInt::getAllOnesValue(ValTy); + ConstantInt* One = ConstantInt::get(Type::Int32Ty, 1); + ConstantInt* ValOne = ConstantInt::get(ValTy, 1); + ConstantInt* Zero = ConstantInt::get(Type::Int32Ty, 0); + ConstantInt* ValZero = ConstantInt::get(ValTy, 0); - BasicBlock* entry = new BasicBlock("entry",F,0); - BasicBlock* large = new BasicBlock("large",F,0); - BasicBlock* small = new BasicBlock("small",F,0); - BasicBlock* forward = new BasicBlock("forward",F,0); - BasicBlock* reverse = new BasicBlock("reverse",F,0); + // Basic blocks we fill in below. + BasicBlock* entry = new BasicBlock("entry", F, 0); + BasicBlock* large = new BasicBlock("large", F, 0); + BasicBlock* small = new BasicBlock("small", F, 0); + BasicBlock* reverse = new BasicBlock("reverse", F, 0); + BasicBlock* result = new BasicBlock("result", F, 0); - // Block entry (entry) + // BASIC BLOCK: entry // First, get the number of bits that we're placing as an i32 ICmpInst* is_forward = new ICmpInst(ICmpInst::ICMP_ULT, Lo, Hi, "", entry); - SelectInst* Lo_pn = new SelectInst(is_forward, Hi, Lo, "", entry); - SelectInst* Hi_pn = new SelectInst(is_forward, Lo, Hi, "", entry); - BinaryOperator* NumBits = BinaryOperator::createSub(Lo_pn, Hi_pn, "",entry); + SelectInst* Hi_pn = new SelectInst(is_forward, Hi, Lo, "", entry); + SelectInst* Lo_pn = new SelectInst(is_forward, Lo, Hi, "", entry); + BinaryOperator* NumBits = BinaryOperator::createSub(Hi_pn, Lo_pn, "",entry); + NumBits = BinaryOperator::createAdd(NumBits, One, "", entry); // Now, convert Lo and Hi to ValTy bit width if (ValBits > 32) { - Hi = new ZExtInst(Hi, ValTy, "", entry); - Lo = new ZExtInst(Lo, ValTy, "", entry); + Lo = new ZExtInst(Lo_pn, ValTy, "", entry); } else if (ValBits < 32) { - Hi = new TruncInst(Hi, ValTy, "", entry); - Lo = new TruncInst(Lo, ValTy, "", entry); + Lo = new TruncInst(Lo_pn, ValTy, "", entry); } // Determine if the replacement bits are larger than the number of bits we // are replacing and deal with it. @@ -538,7 +491,7 @@ static Instruction *LowerPartSet(CallInst *CI) { new ICmpInst(ICmpInst::ICMP_ULT, NumBits, RepBitWidth, "", entry); new BranchInst(large, small, is_large, entry); - // Block "large" + // BASIC BLOCK: large Instruction* MaskBits = BinaryOperator::createSub(RepBitWidth, NumBits, "", large); MaskBits = CastInst::createIntegerCast(MaskBits, RepMask->getType(), @@ -548,7 +501,7 @@ static Instruction *LowerPartSet(CallInst *CI) { BinaryOperator* Rep2 = BinaryOperator::createAnd(Mask1, Rep, "", large); new BranchInst(small, large); - // Block "small" + // BASIC BLOCK: small PHINode* Rep3 = new PHINode(RepTy, "", small); Rep3->reserveOperandSpace(2); Rep3->addIncoming(Rep2, large); @@ -558,37 +511,58 @@ static Instruction *LowerPartSet(CallInst *CI) { Rep4 = new ZExtInst(Rep3, ValTy, "", small); else if (ValBits < RepBits) Rep4 = new TruncInst(Rep3, ValTy, "", small); - ICmpInst* is_reverse = - new ICmpInst(ICmpInst::ICMP_UGT, Lo, Hi, "", small); - new BranchInst(reverse, forward, is_reverse, small); + new BranchInst(result, reverse, is_forward, small); - // Block "forward" - Value* t1 = BinaryOperator::createLShr(ValMask, Hi, "", forward); - Value* t2 = BinaryOperator::createShl(t1, Lo, "", forward); - Value* nott2 = BinaryOperator::createXor(t2, ValMask, "", forward); - Value* t3 = BinaryOperator::createShl(Rep4, Lo, "", forward); - Value* t4 = BinaryOperator::createAnd(nott2, Val, "", forward); - Value* FRslt = BinaryOperator::createOr(t3, t4, "part_set_fwd", forward); - new ReturnInst(FRslt, forward); + // BASIC BLOCK: reverse (reverses the bits of the replacement) + // Set up our loop counter as a PHI so we can decrement on each iteration. + // We will loop for the number of bits in the replacement value. + PHINode *Count = new PHINode(Type::Int32Ty, "count", reverse); + Count->reserveOperandSpace(2); + Count->addIncoming(NumBits, small); - // Block "reverse" - Value* t5 = BinaryOperator::createShl(ValMask, Lo, "", reverse); - Value* t6 = BinaryOperator::createShl(ValMask, Hi, "", reverse); - Value* t7 = BinaryOperator::createOr(t6, t5, "", reverse); - Value* t8 = BinaryOperator::createXor(t7, ValMask, "", reverse); - Value* t9 = BinaryOperator::createAnd(t8, Val, "", reverse); - Value* t10 = BinaryOperator::createShl(Rep4, Lo, "", reverse); - if (32 < ValBits) - RepBitWidth = - cast(ConstantExpr::getZExt(RepBitWidth, ValTy)); - else if (32 > ValBits) - RepBitWidth = - cast(ConstantExpr::getTrunc(RepBitWidth, ValTy)); - Value* t11 = BinaryOperator::createSub(RepBitWidth, Hi, "", reverse); - Value* t13 = BinaryOperator::createLShr(Rep4, t11, "",reverse); - Value* t14 = BinaryOperator::createOr(t10, t9, "", reverse); - Value* RRslt = BinaryOperator::createOr(t14, t13, "part_set_rvrs", reverse); - new ReturnInst(RRslt, reverse); + // Get the value that we are shifting bits out of as a PHI because + // we'll change this with each iteration. + PHINode *BitsToShift = new PHINode(Val->getType(), "val", reverse); + BitsToShift->reserveOperandSpace(2); + BitsToShift->addIncoming(Rep4, small); + + // Get the result of the last computation or zero on first iteration + PHINode *RRes = new PHINode(Val->getType(), "rres", reverse); + RRes->reserveOperandSpace(2); + RRes->addIncoming(ValZero, small); + + // Decrement the loop counter by one + Instruction *Decr = BinaryOperator::createSub(Count, One, "", reverse); + Count->addIncoming(Decr, reverse); + + // Get the bit that we want to move into the result + Value *Bit = BinaryOperator::createAnd(BitsToShift, ValOne, "", reverse); + + // Compute the new value of the bits to shift for the next iteration. + Value *NewVal = BinaryOperator::createLShr(BitsToShift, ValOne,"", reverse); + BitsToShift->addIncoming(NewVal, reverse); + + // Shift the bit we extracted into the low bit of the result. + Instruction *NewRes = BinaryOperator::createShl(RRes, ValOne, "", reverse); + NewRes = BinaryOperator::createOr(NewRes, Bit, "", reverse); + RRes->addIncoming(NewRes, reverse); + + // Terminate loop if we've moved all the bits. + ICmpInst *Cond = new ICmpInst(ICmpInst::ICMP_EQ, Decr, Zero, "", reverse); + new BranchInst(result, reverse, Cond, reverse); + + // BASIC BLOCK: result + PHINode *Rplcmnt = new PHINode(Val->getType(), "", result); + Rplcmnt->reserveOperandSpace(2); + Rplcmnt->addIncoming(NewRes, reverse); + Rplcmnt->addIncoming(Rep4, small); + Value* t0 = CastInst::createIntegerCast(NumBits,ValTy,false,"",result); + Value* t1 = BinaryOperator::createShl(ValMask, t0, "", result); + Value* t2 = BinaryOperator::createShl(t1, Lo, "", result); + Value* t3 = BinaryOperator::createAnd(t2, Val, "", result); + Value* t4 = BinaryOperator::createShl(Rplcmnt, Lo, "", result); + Value* Rslt = BinaryOperator::createOr(t3, t4, "part_set", result); + new ReturnInst(Rslt, result); } // Return a call to the implementation function