forked from OSchip/llvm-project
[ARM] Prevent constants from iCmp instruction from being hoisted if part of a min(max()) pattern
Marks constants of an ICmp instruction as free if it's only user is a select instruction that is part of a min(max()) pattern. Ensures that in loops, in particular when loop unrolling is turned on, SSAT will still be correctly generated. Differential Revision: https://reviews.llvm.org/D88662
This commit is contained in:
Meera Nakrani
parent
067add7b5f
commit
f7c0e2b8f2
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@ -362,8 +362,12 @@ int ARMTTIImpl::getIntImmCostInst(unsigned Opcode, unsigned Idx,
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// Ensures negative constant of min(max()) or max(min()) patterns that
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// Ensures negative constant of min(max()) or max(min()) patterns that
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// match to SSAT instructions don't get hoisted
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// match to SSAT instructions don't get hoisted
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if (Inst && ((ST->hasV6Ops() && !ST->isThumb()) || ST->isThumb2()) &&
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if (Inst && ((ST->hasV6Ops() && !ST->isThumb()) || ST->isThumb2()) &&
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Ty->getIntegerBitWidth() <= 32 && isSSATMinMaxPattern(Inst, Imm))
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Ty->getIntegerBitWidth() <= 32) {
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return 0;
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if (isSSATMinMaxPattern(Inst, Imm) ||
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(isa<ICmpInst>(Inst) && Inst->hasOneUse() &&
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isSSATMinMaxPattern(cast<Instruction>(*Inst->user_begin()), Imm)))
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return 0;
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}
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return getIntImmCost(Imm, Ty, CostKind);
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return getIntImmCost(Imm, Ty, CostKind);
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}
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}
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@ -0,0 +1,123 @@
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; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
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; RUN: llc -mtriple=armv6t2-eabi %s -o - | FileCheck %s --check-prefix=CHECK
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; Checks SSAT is still generated when loop unrolling is on
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define void @ssat_unroll(i16* %pSrcA, i16* %pSrcB, i16* %pDst, i32 %blockSize) {
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; CHECK-LABEL: ssat_unroll:
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; CHECK: @ %bb.0: @ %entry
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; CHECK-NEXT: .save {r11, lr}
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; CHECK-NEXT: push {r11, lr}
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; CHECK-NEXT: cmp r3, #0
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; CHECK-NEXT: beq .LBB0_5
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; CHECK-NEXT: @ %bb.1: @ %while.body.preheader
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; CHECK-NEXT: sub r12, r3, #1
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; CHECK-NEXT: tst r3, #1
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; CHECK-NEXT: beq .LBB0_3
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; CHECK-NEXT: @ %bb.2: @ %while.body.prol.preheader
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; CHECK-NEXT: ldrsh lr, [r0], #2
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; CHECK-NEXT: ldrsh r3, [r1], #2
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; CHECK-NEXT: smulbb r3, r3, lr
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; CHECK-NEXT: ssat r3, #16, r3, asr #14
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; CHECK-NEXT: strh r3, [r2], #2
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; CHECK-NEXT: mov r3, r12
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; CHECK-NEXT: .LBB0_3: @ %while.body.prol.loopexit
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; CHECK-NEXT: cmp r12, #0
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; CHECK-NEXT: popeq {r11, pc}
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; CHECK-NEXT: .LBB0_4: @ %while.body
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; CHECK-NEXT: @ =>This Inner Loop Header: Depth=1
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; CHECK-NEXT: ldrsh r12, [r0]
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; CHECK-NEXT: subs r3, r3, #2
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; CHECK-NEXT: ldrsh lr, [r1]
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; CHECK-NEXT: smulbb r12, lr, r12
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; CHECK-NEXT: ssat r12, #16, r12, asr #14
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; CHECK-NEXT: strh r12, [r2]
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; CHECK-NEXT: ldrsh r12, [r0, #2]
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; CHECK-NEXT: add r0, r0, #4
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; CHECK-NEXT: ldrsh lr, [r1, #2]
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; CHECK-NEXT: add r1, r1, #4
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; CHECK-NEXT: smulbb r12, lr, r12
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; CHECK-NEXT: ssat r12, #16, r12, asr #14
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; CHECK-NEXT: strh r12, [r2, #2]
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; CHECK-NEXT: add r2, r2, #4
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; CHECK-NEXT: bne .LBB0_4
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; CHECK-NEXT: .LBB0_5: @ %while.end
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; CHECK-NEXT: pop {r11, pc}
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entry:
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%cmp.not7 = icmp eq i32 %blockSize, 0
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br i1 %cmp.not7, label %while.end, label %while.body.preheader
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while.body.preheader: ; preds = %entry
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%0 = add i32 %blockSize, -1
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%xtraiter = and i32 %blockSize, 1
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%lcmp.mod.not = icmp eq i32 %xtraiter, 0
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br i1 %lcmp.mod.not, label %while.body.prol.loopexit, label %while.body.prol.preheader
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while.body.prol.preheader: ; preds = %while.body.preheader
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%incdec.ptr.prol = getelementptr inbounds i16, i16* %pSrcA, i32 1
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%1 = load i16, i16* %pSrcA
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%conv.prol = sext i16 %1 to i32
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%incdec.ptr1.prol = getelementptr inbounds i16, i16* %pSrcB, i32 1
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%2 = load i16, i16* %pSrcB
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%conv2.prol = sext i16 %2 to i32
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%mul.prol = mul nsw i32 %conv2.prol, %conv.prol
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%shr.prol = ashr i32 %mul.prol, 14
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%3 = icmp sgt i32 %shr.prol, -32768
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%4 = select i1 %3, i32 %shr.prol, i32 -32768
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%5 = icmp slt i32 %4, 32767
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%spec.select.i.prol = select i1 %5, i32 %4, i32 32767
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%conv3.prol = trunc i32 %spec.select.i.prol to i16
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%incdec.ptr4.prol = getelementptr inbounds i16, i16* %pDst, i32 1
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store i16 %conv3.prol, i16* %pDst
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br label %while.body.prol.loopexit
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while.body.prol.loopexit: ; preds = %while.body.prol.preheader, %while.body.preheader
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%blkCnt.011.unr = phi i32 [ %blockSize, %while.body.preheader ], [ %0, %while.body.prol.preheader ]
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%pSrcA.addr.010.unr = phi i16* [ %pSrcA, %while.body.preheader ], [ %incdec.ptr.prol, %while.body.prol.preheader ]
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%pDst.addr.09.unr = phi i16* [ %pDst, %while.body.preheader ], [ %incdec.ptr4.prol, %while.body.prol.preheader ]
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%pSrcB.addr.08.unr = phi i16* [ %pSrcB, %while.body.preheader ], [ %incdec.ptr1.prol, %while.body.prol.preheader ]
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%6 = icmp eq i32 %0, 0
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br i1 %6, label %while.end, label %while.body
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while.body: ; preds = %while.body.prol.loopexit, %while.body
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%blkCnt.011 = phi i32 [ %dec.1, %while.body ], [ %blkCnt.011.unr, %while.body.prol.loopexit ]
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%pSrcA.addr.010 = phi i16* [ %incdec.ptr.1, %while.body ], [ %pSrcA.addr.010.unr, %while.body.prol.loopexit ]
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%pDst.addr.09 = phi i16* [ %incdec.ptr4.1, %while.body ], [ %pDst.addr.09.unr, %while.body.prol.loopexit ]
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%pSrcB.addr.08 = phi i16* [ %incdec.ptr1.1, %while.body ], [ %pSrcB.addr.08.unr, %while.body.prol.loopexit ]
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%incdec.ptr = getelementptr inbounds i16, i16* %pSrcA.addr.010, i32 1
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%7 = load i16, i16* %pSrcA.addr.010
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%conv = sext i16 %7 to i32
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%incdec.ptr1 = getelementptr inbounds i16, i16* %pSrcB.addr.08, i32 1
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%8 = load i16, i16* %pSrcB.addr.08
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%conv2 = sext i16 %8 to i32
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%mul = mul nsw i32 %conv2, %conv
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%shr = ashr i32 %mul, 14
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%9 = icmp sgt i32 %shr, -32768
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%10 = select i1 %9, i32 %shr, i32 -32768
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%11 = icmp slt i32 %10, 32767
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%spec.select.i = select i1 %11, i32 %10, i32 32767
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%conv3 = trunc i32 %spec.select.i to i16
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%incdec.ptr4 = getelementptr inbounds i16, i16* %pDst.addr.09, i32 1
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store i16 %conv3, i16* %pDst.addr.09
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%incdec.ptr.1 = getelementptr inbounds i16, i16* %pSrcA.addr.010, i32 2
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%12 = load i16, i16* %incdec.ptr
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%conv.1 = sext i16 %12 to i32
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%incdec.ptr1.1 = getelementptr inbounds i16, i16* %pSrcB.addr.08, i32 2
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%13 = load i16, i16* %incdec.ptr1
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%conv2.1 = sext i16 %13 to i32
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%mul.1 = mul nsw i32 %conv2.1, %conv.1
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%shr.1 = ashr i32 %mul.1, 14
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%14 = icmp sgt i32 %shr.1, -32768
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%15 = select i1 %14, i32 %shr.1, i32 -32768
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%16 = icmp slt i32 %15, 32767
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%spec.select.i.1 = select i1 %16, i32 %15, i32 32767
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%conv3.1 = trunc i32 %spec.select.i.1 to i16
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%incdec.ptr4.1 = getelementptr inbounds i16, i16* %pDst.addr.09, i32 2
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store i16 %conv3.1, i16* %incdec.ptr4
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%dec.1 = add i32 %blkCnt.011, -2
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%cmp.not.1 = icmp eq i32 %dec.1, 0
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br i1 %cmp.not.1, label %while.end, label %while.body
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while.end: ; preds = %while.body, %while.body.prol.loopexit, %entry
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ret void
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}
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