mirror of
https://github.com/RPCS3/llvm-mirror.git
synced 2024-10-21 20:12:56 +02:00
13c6dece14
Here we make ScalarEvolution::isKnownPredicate, indirectly, a little smarter.
Given some relational comparison operator OP, and two AddRec SCEVs, {I,+,S} OP
{J,+,T}, we can reduce this to the comparison I OP J when S == T, both AddRecs
are for the same loop, and both are known not to wrap.
As it turns out, because of the way that backedge-guard expressions can be
leveraged when computing known predicates, this allows indvars to simplify the
if-statement comparison in this loop:
void foo (int *a, int *b, int n) {
for (int i = 0; i < n; ++i) {
if (i > n)
a[i] = b[i] + 1;
}
}
which, somewhat surprisingly, we were not previously optimizing away.
llvm-svn: 245400
48 lines
1.6 KiB
LLVM
48 lines
1.6 KiB
LLVM
; RUN: opt -S -indvars < %s | FileCheck %s
|
|
target datalayout = "E-m:e-i64:64-n32:64"
|
|
target triple = "powerpc64-unknown-linux-gnu"
|
|
|
|
; Function Attrs: nounwind
|
|
define void @foo(i32* nocapture %a, i32* nocapture readonly %b, i32 signext %n) #0 {
|
|
entry:
|
|
|
|
; CHECK-LABEL: @foo
|
|
|
|
%cmp.10 = icmp sgt i32 %n, 0
|
|
br i1 %cmp.10, label %for.body.lr.ph, label %for.cond.cleanup
|
|
|
|
for.body.lr.ph: ; preds = %entry
|
|
br label %for.body
|
|
|
|
for.cond.for.cond.cleanup_crit_edge: ; preds = %for.inc
|
|
br label %for.cond.cleanup
|
|
|
|
for.cond.cleanup: ; preds = %for.cond.for.cond.cleanup_crit_edge, %entry
|
|
ret void
|
|
|
|
for.body: ; preds = %for.body.lr.ph, %for.inc
|
|
%i.011 = phi i32 [ 0, %for.body.lr.ph ], [ %inc, %for.inc ]
|
|
%cmp1 = icmp sgt i32 %i.011, %n
|
|
br i1 %cmp1, label %if.then, label %for.inc
|
|
|
|
; CHECK-NOT: br i1 %cmp1, label %if.then, label %for.inc
|
|
; CHECK: br i1 false, label %if.then, label %for.inc
|
|
|
|
if.then: ; preds = %for.body
|
|
%idxprom = sext i32 %i.011 to i64
|
|
%arrayidx = getelementptr inbounds i32, i32* %b, i64 %idxprom
|
|
%0 = load i32, i32* %arrayidx, align 4
|
|
%add = add nsw i32 %0, 1
|
|
%arrayidx3 = getelementptr inbounds i32, i32* %a, i64 %idxprom
|
|
store i32 %add, i32* %arrayidx3, align 4
|
|
br label %for.inc
|
|
|
|
for.inc: ; preds = %for.body, %if.then
|
|
%inc = add nsw i32 %i.011, 1
|
|
%cmp = icmp slt i32 %inc, %n
|
|
br i1 %cmp, label %for.body, label %for.cond.for.cond.cleanup_crit_edge
|
|
}
|
|
|
|
attributes #0 = { nounwind }
|
|
|