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673e1f9ddf
Summary: Currently LowerTypeTests emits jumptable entries for all live external and address-taken functions; however, we could limit the number of functions that we emit entries for significantly. For Cross-DSO CFI, we continue to emit jumptable entries for all exported definitions. In the non-Cross-DSO CFI case, we only need to emit jumptable entries for live functions that are address-taken in live functions. This ignores exported functions and functions that are only address taken in dead functions. This change uses ThinLTO summary data (now emitted for all modules during ThinLTO builds) to determine address-taken and liveness info. The logic for emitting jumptable entries is more conservative in the regular LTO case because we don't have summary data in the case of monolithic LTO builds; however, once summaries are emitted for all LTO builds we can unify the Thin/monolithic LTO logic to only use summaries to determine the liveness of address taking functions. This change is a partial fix for PR37474. It reduces the build size for nacl_helper by ~2-3%, the reduction is due to nacl_helper compiling in lots of unused code and unused functions that are address taken in dead functions no longer being being considered live due to emitted jumptable references. The reduction for chromium is ~0.1-0.2%. Reviewers: pcc, eugenis, javed.absar Reviewed By: pcc Subscribers: aheejin, dexonsmith, dschuff, mehdi_amini, eraman, steven_wu, llvm-commits, kcc Differential Revision: https://reviews.llvm.org/D47652 llvm-svn: 337038
38 lines
1.2 KiB
LLVM
38 lines
1.2 KiB
LLVM
; RUN: opt -thinlto-bc %s -o %t1.bc
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; RUN: llvm-lto2 run -thinlto-distributed-indexes %t1.bc -o %t.out -save-temps \
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; RUN: -r %t1.bc,foo,plx \
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; RUN: -r %t1.bc,bar,x \
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; RUN: -r %t1.bc,addrtaken,px
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; RUN: llvm-bcanalyzer -dump %t.out.index.bc | FileCheck %s --check-prefix=COMBINED
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target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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define i1 @foo(i8* %p) !type !0 {
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entry:
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%x = call i1 @llvm.type.test(i8* %p, metadata !"typeid1")
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ret i1 %x
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}
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declare !type !0 i1 @bar(i8*)
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; Functions must be address taken to have jump table entries emitted
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define void @addrtaken(i1 %i) {
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%1 = select i1 %i, i1(i8*)* @foo, i1(i8*)* @bar
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ret void
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}
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declare i1 @llvm.type.test(i8* %ptr, metadata %type) nounwind readnone
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!0 = !{i64 0, !"typeid1"}
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; COMBINED: <GLOBALVAL_SUMMARY_BLOCK
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; COMBINED: <CFI_FUNCTION_DEFS op0=0 op1=3/>
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; COMBINED: <CFI_FUNCTION_DECLS op0=3 op1=3/>
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; COMBINED: <TYPE_ID op0=6 op1=7 op2=4 op3=7 op4=0 op5=0 op6=0 op7=0/>
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; COMBINED: </GLOBALVAL_SUMMARY_BLOCK>
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; COMBINED: <STRTAB_BLOCK
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; COMBINED-NEXT: <BLOB abbrevid=4/> blob data = 'foobartypeid1'
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; COMBINED-NEXT: </STRTAB_BLOCK>
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