df49d1bbb2
This pass implements whole program optimization of virtual calls in cases where we know (via bitset information) that the list of callees is fixed. This includes the following: - Single implementation devirtualization: if a virtual call has a single possible callee, replace all calls with a direct call to that callee. - Virtual constant propagation: if the virtual function's return type is an integer <=64 bits and all possible callees are readnone, for each class and each list of constant arguments: evaluate the function, store the return value alongside the virtual table, and rewrite each virtual call as a load from the virtual table. - Uniform return value optimization: if the conditions for virtual constant propagation hold and each function returns the same constant value, replace each virtual call with that constant. - Unique return value optimization for i1 return values: if the conditions for virtual constant propagation hold and a single vtable's function returns 0, or a single vtable's function returns 1, replace each virtual call with a comparison of the vptr against that vtable's address. Differential Revision: http://reviews.llvm.org/D16795 llvm-svn: 260312
80 lines
3.0 KiB
LLVM
80 lines
3.0 KiB
LLVM
; RUN: opt -S -wholeprogramdevirt %s | FileCheck %s
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target datalayout = "e-p:64:64"
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target triple = "x86_64-unknown-linux-gnu"
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; CHECK: private constant { [8 x i8], [1 x i8*], [0 x i8] } { [8 x i8] c"\00\00\00\00\00\00\00\01", [1 x i8*] [i8* bitcast (i1 (i8*, i32)* @vf1 to i8*)], [0 x i8] zeroinitializer }
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; CHECK: private constant { [8 x i8], [1 x i8*], [0 x i8] } { [8 x i8] c"\00\00\00\00\00\00\00\02", [1 x i8*] [i8* bitcast (i1 (i8*, i32)* @vf2 to i8*)], [0 x i8] zeroinitializer }
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; CHECK: private constant { [8 x i8], [1 x i8*], [0 x i8] } { [8 x i8] c"\00\00\00\00\00\00\00\01", [1 x i8*] [i8* bitcast (i1 (i8*, i32)* @vf4 to i8*)], [0 x i8] zeroinitializer }
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; CHECK: private constant { [8 x i8], [1 x i8*], [0 x i8] } { [8 x i8] c"\00\00\00\00\00\00\00\02", [1 x i8*] [i8* bitcast (i1 (i8*, i32)* @vf8 to i8*)], [0 x i8] zeroinitializer }
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@vt1 = constant [1 x i8*] [i8* bitcast (i1 (i8*, i32)* @vf1 to i8*)]
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@vt2 = constant [1 x i8*] [i8* bitcast (i1 (i8*, i32)* @vf2 to i8*)]
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@vt4 = constant [1 x i8*] [i8* bitcast (i1 (i8*, i32)* @vf4 to i8*)]
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@vt8 = constant [1 x i8*] [i8* bitcast (i1 (i8*, i32)* @vf8 to i8*)]
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define i1 @vf1(i8* %this, i32 %arg) readnone {
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%and = and i32 %arg, 1
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%cmp = icmp ne i32 %and, 0
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ret i1 %cmp
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}
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define i1 @vf2(i8* %this, i32 %arg) readnone {
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%and = and i32 %arg, 2
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%cmp = icmp ne i32 %and, 0
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ret i1 %cmp
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}
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define i1 @vf4(i8* %this, i32 %arg) readnone {
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%and = and i32 %arg, 4
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%cmp = icmp ne i32 %and, 0
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ret i1 %cmp
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}
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define i1 @vf8(i8* %this, i32 %arg) readnone {
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%and = and i32 %arg, 8
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%cmp = icmp ne i32 %and, 0
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ret i1 %cmp
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}
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; CHECK: define i1 @call1
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define i1 @call1(i8* %obj) {
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%vtableptr = bitcast i8* %obj to [1 x i8*]**
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%vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
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%vtablei8 = bitcast [1 x i8*]* %vtable to i8*
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%p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
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call void @llvm.assume(i1 %p)
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%fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0
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%fptr = load i8*, i8** %fptrptr
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%fptr_casted = bitcast i8* %fptr to i1 (i8*, i32)*
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; CHECK: getelementptr {{.*}} -1
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; CHECK: and {{.*}}, 1
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%result = call i1 %fptr_casted(i8* %obj, i32 5)
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ret i1 %result
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}
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; CHECK: define i1 @call2
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define i1 @call2(i8* %obj) {
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%vtableptr = bitcast i8* %obj to [1 x i8*]**
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%vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
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%vtablei8 = bitcast [1 x i8*]* %vtable to i8*
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%p = call i1 @llvm.bitset.test(i8* %vtablei8, metadata !"bitset")
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call void @llvm.assume(i1 %p)
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%fptrptr = getelementptr [1 x i8*], [1 x i8*]* %vtable, i32 0, i32 0
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%fptr = load i8*, i8** %fptrptr
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%fptr_casted = bitcast i8* %fptr to i1 (i8*, i32)*
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; CHECK: getelementptr {{.*}} -1
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; CHECK: and {{.*}}, 2
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%result = call i1 %fptr_casted(i8* %obj, i32 10)
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ret i1 %result
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}
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declare i1 @llvm.bitset.test(i8*, metadata)
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declare void @llvm.assume(i1)
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!0 = !{!"bitset", [1 x i8*]* @vt1, i32 0}
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!1 = !{!"bitset", [1 x i8*]* @vt2, i32 0}
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!2 = !{!"bitset", [1 x i8*]* @vt4, i32 0}
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!3 = !{!"bitset", [1 x i8*]* @vt8, i32 0}
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!llvm.bitsets = !{!0, !1, !2, !3}
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