[llvm] r217953 - [IndVarSimplify] Widen loop compare instructions.
Chad Rosier
mcrosier at codeaurora.org
Wed Sep 17 07:10:34 PDT 2014
Author: mcrosier
Date: Wed Sep 17 09:10:33 2014
New Revision: 217953
URL: http://llvm.org/viewvc/llvm-project?rev=217953&view=rev
Log:
[IndVarSimplify] Widen loop compare instructions.
This improves other optimizations such as LSR. A sext may be added to the
compare's other operand, but this can often be hoisted outside of the loop.
Added:
llvm/trunk/test/Transforms/IndVarSimplify/widen-loop-comp.ll
Modified:
llvm/trunk/lib/Transforms/Scalar/IndVarSimplify.cpp
llvm/trunk/test/Transforms/IndVarSimplify/no-iv-rewrite.ll
llvm/trunk/test/Transforms/IndVarSimplify/verify-scev.ll
Modified: llvm/trunk/lib/Transforms/Scalar/IndVarSimplify.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/IndVarSimplify.cpp?rev=217953&r1=217952&r2=217953&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/IndVarSimplify.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/IndVarSimplify.cpp Wed Sep 17 09:10:33 2014
@@ -762,6 +762,8 @@ protected:
Instruction *WidenIVUse(NarrowIVDefUse DU, SCEVExpander &Rewriter);
+ bool WidenLoopCompare(NarrowIVDefUse DU);
+
void pushNarrowIVUsers(Instruction *NarrowDef, Instruction *WideDef);
};
} // anonymous namespace
@@ -926,6 +928,32 @@ static void truncateIVUse(NarrowIVDefUse
DU.NarrowUse->replaceUsesOfWith(DU.NarrowDef, Trunc);
}
+/// If the narrow use is a compare instruction, then widen the compare
+// (and possibly the other operand). The extend operation is hoisted into the
+// loop preheader as far as possible.
+bool WidenIV::WidenLoopCompare(NarrowIVDefUse DU) {
+ ICmpInst *Cmp = dyn_cast<ICmpInst>(DU.NarrowUse);
+ if (!Cmp)
+ return false;
+
+ Value *Op = Cmp->getOperand(Cmp->getOperand(0) == DU.NarrowDef ? 1 : 0);
+ unsigned CastWidth = SE->getTypeSizeInBits(Op->getType());
+ unsigned IVWidth = SE->getTypeSizeInBits(WideType);
+ assert (CastWidth <= IVWidth && "Unexpected width while widening compare.");
+
+ // Widen the compare instruction.
+ IRBuilder<> Builder(getInsertPointForUses(DU.NarrowUse, DU.NarrowDef, DT));
+ DU.NarrowUse->replaceUsesOfWith(DU.NarrowDef, DU.WideDef);
+
+ // Widen the other operand of the compare, if necessary.
+ if (CastWidth < IVWidth) {
+ bool IsSigned = CmpInst::isSigned(Cmp->getPredicate());
+ Value *ExtOp = getExtend(Op, WideType, IsSigned, Cmp);
+ DU.NarrowUse->replaceUsesOfWith(Op, ExtOp);
+ }
+ return true;
+}
+
/// WidenIVUse - Determine whether an individual user of the narrow IV can be
/// widened. If so, return the wide clone of the user.
Instruction *WidenIV::WidenIVUse(NarrowIVDefUse DU, SCEVExpander &Rewriter) {
@@ -993,10 +1021,15 @@ Instruction *WidenIV::WidenIVUse(NarrowI
// Does this user itself evaluate to a recurrence after widening?
const SCEVAddRecExpr *WideAddRec = GetWideRecurrence(DU.NarrowUse);
+ if (!WideAddRec)
+ WideAddRec = GetExtendedOperandRecurrence(DU);
+
if (!WideAddRec) {
- WideAddRec = GetExtendedOperandRecurrence(DU);
- }
- if (!WideAddRec) {
+ // If use is a loop condition, try to promote the condition instead of
+ // truncating the IV first.
+ if (WidenLoopCompare(DU))
+ return nullptr;
+
// This user does not evaluate to a recurence after widening, so don't
// follow it. Instead insert a Trunc to kill off the original use,
// eventually isolating the original narrow IV so it can be removed.
Modified: llvm/trunk/test/Transforms/IndVarSimplify/no-iv-rewrite.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/IndVarSimplify/no-iv-rewrite.ll?rev=217953&r1=217952&r2=217953&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/IndVarSimplify/no-iv-rewrite.ll (original)
+++ llvm/trunk/test/Transforms/IndVarSimplify/no-iv-rewrite.ll Wed Sep 17 09:10:33 2014
@@ -229,10 +229,11 @@ entry:
; loop and the OR instruction is replaced by an ADD keeping the result
; equivalent.
;
+; CHECK: sext
; CHECK: loop:
; CHECK: phi i64
; CHECK-NOT: sext
-; CHECK: icmp slt i32
+; CHECK: icmp slt i64
; CHECK: exit:
; CHECK: add i64
loop:
Modified: llvm/trunk/test/Transforms/IndVarSimplify/verify-scev.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/IndVarSimplify/verify-scev.ll?rev=217953&r1=217952&r2=217953&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/IndVarSimplify/verify-scev.ll (original)
+++ llvm/trunk/test/Transforms/IndVarSimplify/verify-scev.ll Wed Sep 17 09:10:33 2014
@@ -380,11 +380,11 @@ for.body48:
for.body65.lr.ph: ; preds = %for.body48
%0 = load i32* undef, align 4
+ %1 = sext i32 %0 to i64
br label %for.body65.us
for.body65.us: ; preds = %for.inc219.us, %for.body65.lr.ph
- %k.09.us = phi i32 [ %inc.us, %for.inc219.us ], [ 1, %for.body65.lr.ph ]
- %idxprom66.us = sext i32 %k.09.us to i64
+ %indvars.iv = phi i64 [ %indvars.iv.next, %for.inc219.us ], [ 1, %for.body65.lr.ph ]
br i1 undef, label %for.inc219.us, label %if.end72.us
if.end72.us: ; preds = %for.body65.us
@@ -406,8 +406,8 @@ for.cond152.us:
br i1 undef, label %for.cond139.loopexit.us, label %for.cond152.us
for.inc219.us: ; preds = %for.cond139.loopexit.us, %if.end110.us, %if.end93.us, %for.body65.us
- %inc.us = add nsw i32 %k.09.us, 1
- %cmp64.us = icmp sgt i32 %inc.us, %0
+ %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+ %cmp64.us = icmp sgt i64 %indvars.iv.next, %1
br i1 %cmp64.us, label %for.inc221, label %for.body65.us
for.cond139.loopexit.us: ; preds = %for.cond152.us
Added: llvm/trunk/test/Transforms/IndVarSimplify/widen-loop-comp.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/IndVarSimplify/widen-loop-comp.ll?rev=217953&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/IndVarSimplify/widen-loop-comp.ll (added)
+++ llvm/trunk/test/Transforms/IndVarSimplify/widen-loop-comp.ll Wed Sep 17 09:10:33 2014
@@ -0,0 +1,166 @@
+; RUN: opt < %s -indvars -S | FileCheck %s
+target triple = "aarch64--linux-gnu"
+
+; Check the loop exit i32 compare instruction and operand are widened to i64
+; instead of truncating IV before its use in the i32 compare instruction.
+
+ at idx = common global i32 0, align 4
+ at e = common global i32 0, align 4
+ at ptr = common global i32* null, align 8
+
+; CHECK-LABEL: @test1
+; CHECK: for.body.lr.ph:
+; CHECK: sext i32
+; CHECK: for.cond:
+; CHECK: icmp slt i64
+; CHECK: for.body:
+; CHECK: phi i64
+
+define i32 @test1() {
+entry:
+ store i32 -1, i32* @idx, align 4
+ %0 = load i32* @e, align 4
+ %cmp4 = icmp slt i32 %0, 0
+ br i1 %cmp4, label %for.end.loopexit, label %for.body.lr.ph
+
+for.body.lr.ph:
+ %1 = load i32** @ptr, align 8
+ %2 = load i32* @e, align 4
+ br label %for.body
+
+for.cond:
+ %inc = add nsw i32 %i.05, 1
+ %cmp = icmp slt i32 %i.05, %2
+ br i1 %cmp, label %for.body, label %for.cond.for.end.loopexit_crit_edge
+
+for.body:
+ %i.05 = phi i32 [ 0, %for.body.lr.ph ], [ %inc, %for.cond ]
+ %idxprom = sext i32 %i.05 to i64
+ %arrayidx = getelementptr inbounds i32* %1, i64 %idxprom
+ %3 = load i32* %arrayidx, align 4
+ %tobool = icmp eq i32 %3, 0
+ br i1 %tobool, label %if.then, label %for.cond
+
+if.then:
+ %i.05.lcssa = phi i32 [ %i.05, %for.body ]
+ store i32 %i.05.lcssa, i32* @idx, align 4
+ br label %for.end
+
+for.cond.for.end.loopexit_crit_edge:
+ br label %for.end.loopexit
+
+for.end.loopexit:
+ br label %for.end
+
+for.end:
+ %4 = load i32* @idx, align 4
+ ret i32 %4
+}
+
+; CHECK-LABEL: @test2
+; CHECK: for.body4.us
+; CHECK: %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+; CHECK: %cmp2.us = icmp slt i64
+; CHECK-NOT: %2 = trunc i64 %indvars.iv.next to i32
+; CHECK-NOT: %cmp2.us = icmp slt i32
+
+define void @test2([8 x i8]* %a, i8* %b, i8 %limit) {
+entry:
+ %conv = zext i8 %limit to i32
+ %cmp23 = icmp eq i8 %limit, 0
+ br i1 %cmp23, label %for.cond1.preheader, label %for.cond1.preheader.us
+
+for.cond1.preheader.us:
+ %storemerge5.us = phi i32 [ 0, %entry ], [ %inc14.us, %for.inc13.us ]
+ br i1 true, label %for.body4.lr.ph.us, label %for.inc13.us
+
+for.inc13.us:
+ %inc14.us = add nsw i32 %storemerge5.us, 1
+ %cmp.us = icmp slt i32 %inc14.us, 4
+ br i1 %cmp.us, label %for.cond1.preheader.us, label %for.end
+
+for.body4.us:
+ %storemerge14.us = phi i32 [ 0, %for.body4.lr.ph.us ], [ %inc.us, %for.body4.us ]
+ %idxprom.us = sext i32 %storemerge14.us to i64
+ %arrayidx6.us = getelementptr inbounds [8 x i8]* %a, i64 %idxprom5.us, i64 %idxprom.us
+ %0 = load i8* %arrayidx6.us, align 1
+ %idxprom7.us = zext i8 %0 to i64
+ %arrayidx8.us = getelementptr inbounds i8* %b, i64 %idxprom7.us
+ %1 = load i8* %arrayidx8.us, align 1
+ store i8 %1, i8* %arrayidx6.us, align 1
+ %inc.us = add nsw i32 %storemerge14.us, 1
+ %cmp2.us = icmp slt i32 %inc.us, %conv
+ br i1 %cmp2.us, label %for.body4.us, label %for.inc13.us
+
+for.body4.lr.ph.us:
+ %idxprom5.us = sext i32 %storemerge5.us to i64
+ br label %for.body4.us
+
+for.cond1.preheader:
+ %storemerge5 = phi i32 [ 0, %entry ], [ %inc14, %for.inc13 ]
+ br i1 false, label %for.inc13, label %for.inc13
+
+for.inc13:
+ %inc14 = add nsw i32 %storemerge5, 1
+ %cmp = icmp slt i32 %inc14, 4
+ br i1 %cmp, label %for.cond1.preheader, label %for.end
+
+for.end:
+ ret void
+}
+
+; CHECK-LABEL: @test3
+; CHECK: sext i32 %b
+; CHECK: for.cond:
+; CHECK: phi i64
+; CHECK: icmp slt i64
+
+define i32 @test3(i32* %a, i32 %b) {
+entry:
+ br label %for.cond
+
+for.cond:
+ %sum.0 = phi i32 [ 0, %entry ], [ %add, %for.body ]
+ %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
+ %cmp = icmp slt i32 %i.0, %b
+ br i1 %cmp, label %for.body, label %for.end
+
+for.body:
+ %idxprom = sext i32 %i.0 to i64
+ %arrayidx = getelementptr inbounds i32* %a, i64 %idxprom
+ %0 = load i32* %arrayidx, align 4
+ %add = add nsw i32 %sum.0, %0
+ %inc = add nsw i32 %i.0, 1
+ br label %for.cond
+
+for.end:
+ ret i32 %sum.0
+}
+
+; CHECK-LABEL: @test4
+; CHECK: zext i32 %b
+; CHECK: for.cond:
+; CHECK: phi i64
+; CHECK: icmp ule i64
+
+define i32 @test4(i32* %a, i32 %b) {
+entry:
+ br label %for.cond
+
+for.cond:
+ %sum.0 = phi i32 [ 0, %entry ], [ %add, %for.body ]
+ %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
+ %cmp = icmp ule i32 %i.0, %b
+ br i1 %cmp, label %for.body, label %for.end
+
+for.body:
+ %idxprom = sext i32 %i.0 to i64
+ %arrayidx = getelementptr inbounds i32* %a, i64 %idxprom
+ %0 = load i32* %arrayidx, align 4
+ %add = add nsw i32 %sum.0, %0
+ %inc = add nsw i32 %i.0, 1
+ br label %for.cond
+
+for.end:
+ ret i32 %sum.0
+}
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