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

[CGP] Ensure splitgep gives deterministic output 

The output of splitLargeGEPOffsets does not appear to be deterministic because
of the way that we iterate over a DenseMap. I've changed it to a MapVector for
consistent output.

The test here isn't particularly great, only showing a consmetic difference in
output. The original reproducer is much larger but show a diffierence in
instruction ordering, leading to different codegen.

Differential Revision: https://reviews.llvm.org/D51851

llvm-svn: 342043
This commit is contained in:
David Green 2018-09-12 10:19:10 +00:00
parent 10fb677285
commit e27e87cdcb
2 changed files with 41 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
llvm/lib/CodeGen/CodeGenPrepare.cpp
View File

@ -278,7 +278,7 @@ class TypePromotionTransaction;
/// Keep track of GEPs accessing the same data structures such as structs or
/// arrays that are candidates to be split later because of their large
/// size.
DenseMap<
MapVector<
AssertingVH<Value>,
SmallVector<std::pair<AssertingVH<GetElementPtrInst>, int64_t>, 32>>
LargeOffsetGEPMap;

40
llvm/test/Transforms/CodeGenPrepare/ARM/splitgep.ll Normal file
View File

@ -0,0 +1,40 @@
; RUN: opt -S -codegenprepare %s | FileCheck %s
target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
target triple = "thumbv6m-arm-none-eabi"
; Check that we have deterministic output
define void @test([65536 x i32]** %sp, [65536 x i32]* %t, i32 %n) {
; CHECK-LABEL: @test(
; CHECK-NEXT: entry:
; CHECK-NEXT: %0 = bitcast [65536 x i32]* %t to i8*
; CHECK-NEXT: %splitgep1 = getelementptr i8, i8* %0, i32 80000
; CHECK-NEXT: %s = load [65536 x i32]*, [65536 x i32]** %sp
; CHECK-NEXT: %1 = bitcast [65536 x i32]* %s to i8*
; CHECK-NEXT: %splitgep = getelementptr i8, i8* %1, i32 80000
entry:
%s = load [65536 x i32]*, [65536 x i32]** %sp
br label %while_cond
while_cond:
%phi = phi i32 [ 0, %entry ], [ %i, %while_body ]
%gep0 = getelementptr [65536 x i32], [65536 x i32]* %s, i64 0, i32 20000
%gep1 = getelementptr [65536 x i32], [65536 x i32]* %s, i64 0, i32 20001
%gep2 = getelementptr [65536 x i32], [65536 x i32]* %t, i64 0, i32 20000
%gep3 = getelementptr [65536 x i32], [65536 x i32]* %t, i64 0, i32 20001
%cmp = icmp slt i32 %phi, %n
br i1 %cmp, label %while_body, label %while_end
while_body:
%i = add i32 %phi, 1
%j = add i32 %phi, 2
store i32 %i, i32* %gep0
store i32 %phi, i32* %gep1
store i32 %i, i32* %gep2
store i32 %phi, i32* %gep3
br label %while_cond
while_end:
ret void
}