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Teach SCEV to look through returned-argument functions

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When building SCEVs, if a function is known to return its argument, then we can
build the SCEV using the corresponding argument value.

Differential Revision: http://reviews.llvm.org/D9381

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275037 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Hal Finkel 2016-07-11 02:48:23 +00:00
parent d90d6130ff
commit 837551f8d6
2 changed files with 23 additions and 0 deletions
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7
lib/Analysis/ScalarEvolution.cpp
View File

@ -5225,6 +5225,13 @@ const SCEV *ScalarEvolution::createSCEV(Value *V) {
if (isa<Instruction>(U))
return createNodeForSelectOrPHI(cast<Instruction>(U), U->getOperand(0),
U->getOperand(1), U->getOperand(2));
break;
case Instruction::Call:
case Instruction::Invoke:
if (Value *RV = CallSite(U).getReturnedArgOperand())
return getSCEV(RV);
break;
}
return getUnknown(V);

16
test/Analysis/ScalarEvolution/returned.ll Normal file
View File

@ -0,0 +1,16 @@
; RUN: opt < %s -S -analyze -scalar-evolution | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
define i8* @foo(i32 %no, i8* nocapture %d) nounwind {
entry:
%v = call i8* @func1(i8* %d)
%w = getelementptr i8, i8* %v, i64 5
ret i8* %w
}
; CHECK-LABEL: Classifying expressions for: @foo
; CHECK: %w = getelementptr i8, i8* %v, i64 5
; CHECK-NEXT: (5 + %d)
declare i8* @func1(i8* returned) nounwind argmemonly