maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

[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.

llvm-svn: 217953
This commit is contained in:
Chad Rosier 2014-09-17 14:10:33 +00:00
parent ebdf90ca00
commit bb99f40530
4 changed files with 208 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

39
llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
View File

@ -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, DominatorTree *DT) {
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(NarrowIVDefUse DU, SCEVExpander &Rewriter) {
// 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.

3
llvm/test/Transforms/IndVarSimplify/no-iv-rewrite.ll
View File

@ -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:

8
llvm/test/Transforms/IndVarSimplify/verify-scev.ll
View File

@ -380,11 +380,11 @@ for.body48: ; preds = %for.inc221, %for.bo
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: ; preds = %for.cond152.us, %fo
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

166
llvm/test/Transforms/IndVarSimplify/widen-loop-comp.ll Normal file
View File

@ -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.
@idx = common global i32 0, align 4
@e = common global i32 0, align 4
@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
}