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Revert "Revert "This patch builds on top of D13378 to handle constant condition.""

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This reverts commit r249528 and reapply r249431. The fix for the
fallout has been commited in r249575.

From: Mehdi Amini <mehdi.amini@apple.com>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@249581 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Mehdi Amini 2015-10-07 18:14:25 +00:00
parent b5f011715c
commit 0ba01f2bb2
2 changed files with 56 additions and 0 deletions
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5
lib/Analysis/ScalarEvolution.cpp
View File

@ -3904,6 +3904,11 @@ const SCEV *ScalarEvolution::createNodeForSelectOrPHI(Instruction *I,
Value *Cond,
Value *TrueVal,
Value *FalseVal) {
// Handle "constant" branch or select. This can occur for instance when a
// loop pass transforms an inner loop and moves on to process the outer loop.
if (auto *CI = dyn_cast<ConstantInt>(Cond))
return getSCEV(CI->isOne() ? TrueVal : FalseVal);
// Try to match some simple smax or umax patterns.
auto *ICI = dyn_cast<ICmpInst>(Cond);
if (!ICI)

51
test/Analysis/ScalarEvolution/constant_condition.ll Normal file
View File

@ -0,0 +1,51 @@
; RUN: opt -analyze -scalar-evolution < %s | FileCheck %s
define i32 @branch_true(i32 %x, i32 %y) {
; CHECK-LABEL: Classifying expressions for: @branch_true
entry:
br i1 true, label %add, label %merge
add:
%sum = add i32 %x, %y
br label %merge
merge:
%v = phi i32 [ %sum, %add ], [ %x, %entry ]
; CHECK: %v = phi i32 [ %sum, %add ], [ %x, %entry ]
; CHECK-NEXT: --> (%x + %y) U: full-set S: full-set
ret i32 %v
}
define i32 @branch_false(i32 %x, i32 %y) {
; CHECK-LABEL: Classifying expressions for: @branch_false
entry:
br i1 false, label %add, label %merge
add:
%sum = add i32 %x, %y
br label %merge
merge:
%v = phi i32 [ %sum, %add ], [ %x, %entry ]
; CHECK: %v = phi i32 [ %sum, %add ], [ %x, %entry ]
; CHECK-NEXT: --> %x U: full-set S: full-set
ret i32 %v
}
define i32 @select_true(i32 %x, i32 %y) {
; CHECK-LABEL: Classifying expressions for: @select_true
entry:
%v = select i1 true, i32 %x, i32 %y
; CHECK: %v = select i1 true, i32 %x, i32 %y
; CHECK-NEXT: --> %x U: full-set S: full-set
ret i32 %v
}
define i32 @select_false(i32 %x, i32 %y) {
; CHECK-LABEL: Classifying expressions for: @select_false
entry:
%v = select i1 false, i32 %x, i32 %y
; CHECK: %v = select i1 false, i32 %x, i32 %y
; CHECK-NEXT: --> %y U: full-set S: full-set
ret i32 %v
}