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05237a905d
This patch adds a new pass for attaching !callees metadata to indirect call sites. The pass propagates values to call sites by performing an IPSCCP-like analysis using the generic sparse propagation solver. For indirect call sites having a small set of possible callees, the attached metadata indicates what those callees are. The metadata can be used to facilitate optimizations like intersecting the function attributes of the possible callees, refining the call graph, performing indirect call promotion, etc. Differential Revision: https://reviews.llvm.org/D37355 llvm-svn: 316576
40 lines
1.3 KiB
LLVM
40 lines
1.3 KiB
LLVM
; RUN: opt -called-value-propagation -S < %s | FileCheck %s
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target triple = "aarch64-unknown-linux-gnueabi"
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@global_function = internal unnamed_addr global void ()* null, align 8
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@global_scalar = internal unnamed_addr global i64 zeroinitializer
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; This test checks that we propagate the functions through a select
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; instruction, and attach !callees metadata to the call. Such metadata can
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; enable optimizations of this code sequence.
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;
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; For example, since both of the targeted functions have the "norecurse"
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; attribute, the function attributes pass can be made to infer that
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; "@test_select" is also norecurse. This would allow the globals optimizer to
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; localize "@global_scalar". The function could then be further simplified to
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; always return the constant "1", eliminating the load and store instructions.
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;
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; CHECK: call void %tmp0(), !callees ![[MD:[0-9]+]]
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; CHECK: ![[MD]] = !{void ()* @norecurse_1, void ()* @norecurse_2}
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;
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define i64 @test_select_entry(i1 %flag) {
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entry:
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%tmp0 = call i64 @test_select(i1 %flag)
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ret i64 %tmp0
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}
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define internal i64 @test_select(i1 %flag) {
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entry:
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%tmp0 = select i1 %flag, void ()* @norecurse_1, void ()* @norecurse_2
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store i64 1, i64* @global_scalar
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call void %tmp0()
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%tmp1 = load i64, i64* @global_scalar
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ret i64 %tmp1
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}
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declare void @norecurse_1() #0
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declare void @norecurse_2() #0
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attributes #0 = { norecurse }
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