6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2026-04-26 12:20:42 +00:00
Code Issues Projects Releases Wiki Activity

Exploit dereferenceable_or_null attribute in LICM pass

Browse Source 
Summary:
Allow hoisting of loads from values marked with dereferenceable_or_null
attribute. For values marked with the attribute perform
context-sensitive analysis to determine whether it's known-non-null or
not.

Patch by Artur Pilipenko!

Reviewers: hfinkel, sanjoy, reames

Reviewed By: reames

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D9253

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237593 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Sanjoy Das
2015-05-18 18:07:00 +00:00
parent 9962fd0e2e
commit 0799eb1140
5 changed files with 237 additions and 43 deletions
Download Patch File Download Diff File Expand all files Collapse all files
test/Transforms/LICM/hoist-deref-load.ll
+90
View File
@@ -164,5 +164,95 @@ for.end: ; preds = %for.inc, %entry
ret void
}
; This test represents the following function:
; void test1(int * __restrict__ a, int *b, int &c, int n) {
; if (c != null)
; for (int i = 0; i < n; ++i)
; if (a[i] > 0)
; a[i] = c*b[i];
; }
; and we want to hoist the load of %c out of the loop. This can be done only
; because the dereferenceable_or_null attribute is on %c and there is a null
; check on %c.
; CHECK-LABEL: @test5
; CHECK: load i32, i32* %c, align 4
; CHECK: for.body:
define void @test5(i32* noalias %a, i32* %b, i32* dereferenceable_or_null(4) %c, i32 %n) #0 {
entry:
%not_null = icmp ne i32* %c, null
br i1 %not_null, label %not.null, label %for.end
not.null:
%cmp11 = icmp sgt i32 %n, 0
br i1 %cmp11, label %for.body, label %for.end
for.body: ; preds = %not.null, %for.inc
%indvars.iv = phi i64 [ %indvars.iv.next, %for.inc ], [ 0, %not.null ]
%arrayidx = getelementptr inbounds i32, i32* %a, i64 %indvars.iv
%0 = load i32, i32* %arrayidx, align 4
%cmp1 = icmp sgt i32 %0, 0
br i1 %cmp1, label %if.then, label %for.inc
if.then: ; preds = %for.body
%1 = load i32, i32* %c, align 4
%arrayidx3 = getelementptr inbounds i32, i32* %b, i64 %indvars.iv
%2 = load i32, i32* %arrayidx3, align 4
%mul = mul nsw i32 %2, %1
store i32 %mul, i32* %arrayidx, align 4
br label %for.inc
for.inc: ; preds = %for.body, %if.then
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
%lftr.wideiv = trunc i64 %indvars.iv.next to i32
%exitcond = icmp eq i32 %lftr.wideiv, %n
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.inc, %entry, %not.null
ret void
}
; This is the same as @test5, but without the null check on %c.
; Without this check, we should not hoist the load of %c.
; This test case has an icmp on c but the use of this comparison is
; not a branch.
; CHECK-LABEL: @test6
; CHECK: if.then:
; CHECK: load i32, i32* %c, align 4
define i1 @test6(i32* noalias %a, i32* %b, i32* dereferenceable_or_null(4) %c, i32 %n) #0 {
entry:
%not_null = icmp ne i32* %c, null
%cmp11 = icmp sgt i32 %n, 0
br i1 %cmp11, label %for.body, label %for.end
for.body: ; preds = %entry, %for.inc
%indvars.iv = phi i64 [ %indvars.iv.next, %for.inc ], [ 0, %entry ]
%arrayidx = getelementptr inbounds i32, i32* %a, i64 %indvars.iv
%0 = load i32, i32* %arrayidx, align 4
%cmp1 = icmp sgt i32 %0, 0
br i1 %cmp1, label %if.then, label %for.inc
if.then: ; preds = %for.body
%1 = load i32, i32* %c, align 4
%arrayidx3 = getelementptr inbounds i32, i32* %b, i64 %indvars.iv
%2 = load i32, i32* %arrayidx3, align 4
%mul = mul nsw i32 %2, %1
store i32 %mul, i32* %arrayidx, align 4
br label %for.inc
for.inc: ; preds = %for.body, %if.then
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
%lftr.wideiv = trunc i64 %indvars.iv.next to i32
%exitcond = icmp eq i32 %lftr.wideiv, %n
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.inc, %entry
ret i1 %not_null
}
attributes #0 = { nounwind uwtable }