maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

[RS4GC] Fix crash in the case that a live variable has a constant base. 

Summary:
Previously, RS4GC crashed in CreateGCRelocates() because it assumed
that every base is also in the array of live variables, which isn't true if a
live variable has a constant base.

This change fixes the crash by making sure CreateGCRelocates() won't try to
relocate a live variable with a constant base.  This would be unnecessary
anyway because anything with a constant base won't move.

Reviewers: reames

Subscribers: llvm-commits, sanjoy

Differential Revision: http://reviews.llvm.org/D15556

llvm-svn: 256252
This commit is contained in:
Manuel Jacob 2015-12-22 16:50:44 +00:00
parent c2961ab889
commit 990dfa6fe5
3 changed files with 52 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
View File

@ -2387,6 +2387,19 @@ static bool insertParsePoints(Function &F, DominatorTree &DT,
}
}
// It is possible that non-constant live variables have a constant base. For
// example, a GEP with a variable offset from a global. In this case we can
// remove it from the liveset. We already don't add constants to the liveset
// because we assume they won't move at runtime and the GC doesn't need to be
// informed about them. The same reasoning applies if the base is constant.
// Note that the relocation placement code relies on this filtering for
// correctness as it expects the base to be in the liveset, which isn't true
// if the base is constant.
for (auto &Info : Records)
for (auto &BasePair : Info.PointerToBase)
if (isa<Constant>(BasePair.second))
Info.LiveSet.erase(BasePair.first);
for (CallInst *CI : Holders)
CI->eraseFromParent();

20
llvm/test/Transforms/RewriteStatepointsForGC/base-pointers-12.ll Normal file
View File

@ -0,0 +1,20 @@
; RUN: opt %s -rewrite-statepoints-for-gc -spp-print-base-pointers -S 2>&1 | FileCheck %s
; CHECK: derived %select base %global
@global = external addrspace(1) global i8
define i8 @test(i1 %cond) gc "statepoint-example" {
%derived1 = getelementptr i8, i8 addrspace(1)* @global, i64 1
%derived2 = getelementptr i8, i8 addrspace(1)* @global, i64 2
%select = select i1 %cond, i8 addrspace(1)* %derived1, i8 addrspace(1)* %derived2
%safepoint_token = call i32 (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 2882400000, i32 0, void ()* @extern, i32 0, i32 0, i32 0, i32 0)
; CHECK-NOT: relocate
; CHECK: %load = load i8, i8 addrspace(1)* %select
%load = load i8, i8 addrspace(1)* %select
ret i8 %load
}
declare void @extern() gc "statepoint-example"
declare i32 @llvm.experimental.gc.statepoint.p0f_isVoidf(i64, i32, void ()*, i32, i32, ...)

19
llvm/test/Transforms/RewriteStatepointsForGC/base-pointers-13.ll Normal file
View File

@ -0,0 +1,19 @@
; RUN: opt %s -rewrite-statepoints-for-gc -spp-print-base-pointers -S 2>&1 | FileCheck %s
; CHECK: derived %derived base %global
@global = external addrspace(1) global i8
define i8 @test(i64 %offset) gc "statepoint-example" {
%derived = getelementptr i8, i8 addrspace(1)* @global, i64 %offset
%safepoint_token = call i32 (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 2882400000, i32 0, void ()* @extern, i32 0, i32 0, i32 0, i32 0)
; CHECK-NOT: relocate
; CHECK-NOT: remat
; CHECK: %load = load i8, i8 addrspace(1)* %derived
%load = load i8, i8 addrspace(1)* %derived
ret i8 %load
}
declare void @extern() gc "statepoint-example"
declare i32 @llvm.experimental.gc.statepoint.p0f_isVoidf(i64, i32, void ()*, i32, i32, ...)