20faf78919
Thinlink provides an opportunity to propagate function attributes across modules, enabling additional propagation opportunities. This change propagates (currently default off, turn on with `disable-thinlto-funcattrs=1`) noRecurse and noUnwind based off of function summaries of the prevailing functions in bottom-up call-graph order. Testing on clang self-build: 1. There's a 35-40% increase in noUnwind functions due to the additional propagation opportunities. 2. Throughput is measured at 10-15% increase in thinlink time which itself is 1.5% of E2E link time. Implementation-wise this adds the following summary function attributes: 1. noUnwind: function is noUnwind 2. mayThrow: function contains a non-call instruction that `Instruction::mayThrow` returns true on (e.g. windows SEH instructions) 3. hasUnknownCall: function contains calls that don't make it into the summary call-graph thus should not be propagated from (e.g. indirect for now, could add no-opt functions as well) Testing: Clang self-build passes and 2nd stage build passes check-all ninja check-all with newly added tests passing Reviewed By: tejohnson Differential Revision: https://reviews.llvm.org/D36850
34 lines
1.5 KiB
LLVM
34 lines
1.5 KiB
LLVM
; This test ensures that we drop the preempted copy of @f from %t2.bc from its
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; comdat after making it available_externally. If not we would get a
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; verification error.
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; RUN: opt -module-summary %s -o %t1.bc
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; RUN: opt -module-summary %p/Inputs/linkonce_resolution_comdat.ll -o %t2.bc
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; RUN: llvm-lto -thinlto-action=run -disable-thinlto-funcattrs=0 %t1.bc %t2.bc -exported-symbol=f -exported-symbol=g -thinlto-save-temps=%t3.
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; RUN: llvm-dis %t3.0.3.imported.bc -o - | FileCheck %s --check-prefix=IMPORT1
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; RUN: llvm-dis %t3.1.3.imported.bc -o - | FileCheck %s --check-prefix=IMPORT2
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; Copy from first module is prevailing and converted to weak_odr, copy
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; from second module is preempted and converted to available_externally and
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; removed from comdat.
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; IMPORT1: define weak_odr i32 @f(i8* %0) unnamed_addr [[ATTR:#[0-9]+]] comdat($c1) {
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; IMPORT2: define available_externally i32 @f(i8* %0) unnamed_addr [[ATTR:#[0-9]+]] {
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; CHECK-DAG: attributes [[ATTR]] = { norecurse nounwind }
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; RUN: llvm-nm -o - < %t1.bc.thinlto.o | FileCheck %s --check-prefix=NM1
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; NM1: W f
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; RUN: llvm-nm -o - < %t2.bc.thinlto.o | FileCheck %s --check-prefix=NM2
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; f() would have been turned into available_externally since it is preempted,
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; and inlined into g()
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; NM2-NOT: f
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target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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$c1 = comdat any
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define linkonce_odr i32 @f(i8*) unnamed_addr comdat($c1) {
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ret i32 43
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}
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