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Fix ScalarEvolution's tripcount computation for chains of loops

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where each loop's induction variable's start value is the exit
value of a preceding loop.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107224 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman
2010-06-29 23:43:06 +00:00
parent 07d3177117
commit 1104645eef
2 changed files with 125 additions and 43 deletions
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66
test/Transforms/IndVarSimplify/tripcount_compute.ll
View File

@@ -1,9 +1,12 @@
; RUN: opt < %s -indvars -S | FileCheck %s
; These tests ensure that we can compute the trip count of various forms of
; loops. If the trip count of the loop is computable, then we will know what
; the exit value of the loop will be for some value, allowing us to substitute
; it directly into users outside of the loop, making the loop dead.
;
; RUN: opt < %s -indvars -loop-deletion -simplifycfg -S | not grep br
; CHECK: @linear_setne
; CHECK: ret i32 100
define i32 @linear_setne() {
entry:
@@ -19,6 +22,9 @@ loopexit: ; preds = %loop
ret i32 %i
}
; CHECK: @linear_setne_2
; CHECK: ret i32 100
define i32 @linear_setne_2() {
entry:
br label %loop
@@ -33,6 +39,9 @@ loopexit: ; preds = %loop
ret i32 %i
}
; CHECK: @linear_setne_overflow
; CHECK: ret i32 0
define i32 @linear_setne_overflow() {
entry:
br label %loop
@@ -47,6 +56,9 @@ loopexit: ; preds = %loop
ret i32 %i
}
; CHECK: @linear_setlt
; CHECK: ret i32 100
define i32 @linear_setlt() {
entry:
br label %loop
@@ -61,6 +73,9 @@ loopexit: ; preds = %loop
ret i32 %i
}
; CHECK: @quadratic_setlt
; CHECK: ret i32 34
define i32 @quadratic_setlt() {
entry:
br label %loop
@@ -76,6 +91,9 @@ loopexit: ; preds = %loop
ret i32 %i
}
; CHECK: @chained
; CHECK: ret i32 200
define i32 @chained() {
entry:
br label %loop
@@ -98,3 +116,47 @@ loop2: ; preds = %loop2, %loopexit
loopexit2: ; preds = %loop2
ret i32 %j
}
; CHECK: @chained4
; CHECK: ret i32 400
define i32 @chained4() {
entry:
br label %loop
loop: ; preds = %loop, %entry
%i = phi i32 [ 0, %entry ], [ %i.next, %loop ] ; <i32> [#uses=3]
%i.next = add i32 %i, 1 ; <i32> [#uses=1]
%c = icmp ne i32 %i.next, 100 ; <i1> [#uses=1]
br i1 %c, label %loop, label %loopexit
loopexit: ; preds = %loop
br label %loop2
loop2: ; preds = %loop2, %loopexit
%j = phi i32 [ %i.next, %loopexit ], [ %j.next, %loop2 ] ; <i32> [#uses=3]
%j.next = add i32 %j, 1 ; <i32> [#uses=1]
%c2 = icmp ne i32 %j.next, 200 ; <i1> [#uses=1]
br i1 %c2, label %loop2, label %loopexit2
loopexit2: ; preds = %loop
br label %loop8
loop8: ; preds = %loop2, %loopexit
%k = phi i32 [ %j.next, %loopexit2 ], [ %k.next, %loop8 ] ; <i32> [#uses=3]
%k.next = add i32 %k, 1 ; <i32> [#uses=1]
%c8 = icmp ne i32 %k.next, 300 ; <i1> [#uses=1]
br i1 %c8, label %loop8, label %loopexit8
loopexit8: ; preds = %loop2
br label %loop9
loop9: ; preds = %loop2, %loopexit
%l = phi i32 [ %k.next, %loopexit8 ], [ %l.next, %loop9 ] ; <i32> [#uses=3]
%l.next = add i32 %l, 1 ; <i32> [#uses=1]
%c9 = icmp ne i32 %l.next, 400 ; <i1> [#uses=1]
br i1 %c9, label %loop9, label %loopexit9
loopexit9: ; preds = %loop2
ret i32 %l.next
}