зеркало из https://github.com/mozilla/gecko-dev.git
101 строка
3.9 KiB
Diff
101 строка
3.9 KiB
Diff
From d1c09fb47e2778538c5b1f918724d31d05497883 Mon Sep 17 00:00:00 2001
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From: Arthur Eubanks <aeubanks@google.com>
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Date: Wed, 13 May 2020 16:33:09 -0700
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Subject: [PATCH] Don't jump to landing pads in Control Flow Optimizer
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Summary: Likely fixes https://bugs.llvm.org/show_bug.cgi?id=45858.
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Subscribers: hiraditya, llvm-commits
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Tags: #llvm
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Differential Revision: https://reviews.llvm.org/D80047
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---
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llvm/lib/CodeGen/BranchFolding.cpp | 18 ++++++------
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llvm/test/CodeGen/X86/branchfolding-ehpad.mir | 28 +++++++++++++++++++
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2 files changed, 38 insertions(+), 8 deletions(-)
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create mode 100644 llvm/test/CodeGen/X86/branchfolding-ehpad.mir
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diff --git a/llvm/lib/CodeGen/BranchFolding.cpp b/llvm/lib/CodeGen/BranchFolding.cpp
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index fb54b5d6c8d..4a822b58446 100644
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--- a/llvm/lib/CodeGen/BranchFolding.cpp
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+++ b/llvm/lib/CodeGen/BranchFolding.cpp
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@@ -991,10 +991,10 @@ bool BranchFolder::TryTailMergeBlocks(MachineBasicBlock *SuccBB,
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continue;
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}
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- // If one of the blocks is the entire common tail (and not the entry
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- // block, which we can't jump to), we can treat all blocks with this same
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- // tail at once. Use PredBB if that is one of the possibilities, as that
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- // will not introduce any extra branches.
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+ // If one of the blocks is the entire common tail (and is not the entry
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+ // block/an EH pad, which we can't jump to), we can treat all blocks with
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+ // this same tail at once. Use PredBB if that is one of the possibilities,
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+ // as that will not introduce any extra branches.
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MachineBasicBlock *EntryBB =
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&MergePotentials.front().getBlock()->getParent()->front();
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unsigned commonTailIndex = SameTails.size();
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@@ -1002,19 +1002,21 @@ bool BranchFolder::TryTailMergeBlocks(MachineBasicBlock *SuccBB,
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// into the other.
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if (SameTails.size() == 2 &&
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SameTails[0].getBlock()->isLayoutSuccessor(SameTails[1].getBlock()) &&
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- SameTails[1].tailIsWholeBlock())
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+ SameTails[1].tailIsWholeBlock() && !SameTails[1].getBlock()->isEHPad())
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commonTailIndex = 1;
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else if (SameTails.size() == 2 &&
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SameTails[1].getBlock()->isLayoutSuccessor(
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- SameTails[0].getBlock()) &&
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- SameTails[0].tailIsWholeBlock())
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+ SameTails[0].getBlock()) &&
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+ SameTails[0].tailIsWholeBlock() &&
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+ !SameTails[0].getBlock()->isEHPad())
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commonTailIndex = 0;
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else {
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// Otherwise just pick one, favoring the fall-through predecessor if
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// there is one.
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for (unsigned i = 0, e = SameTails.size(); i != e; ++i) {
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MachineBasicBlock *MBB = SameTails[i].getBlock();
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- if (MBB == EntryBB && SameTails[i].tailIsWholeBlock())
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+ if ((MBB == EntryBB || MBB->isEHPad()) &&
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+ SameTails[i].tailIsWholeBlock())
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continue;
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if (MBB == PredBB) {
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commonTailIndex = i;
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diff --git a/llvm/test/CodeGen/X86/branchfolding-ehpad.mir b/llvm/test/CodeGen/X86/branchfolding-ehpad.mir
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new file mode 100644
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index 00000000000..d445cd20680
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--- /dev/null
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+++ b/llvm/test/CodeGen/X86/branchfolding-ehpad.mir
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@@ -0,0 +1,28 @@
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+# RUN: llc -mtriple=x86_64-windows-msvc -verify-machineinstrs -run-pass branch-folder -o - %s | FileCheck %s
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+
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+# Check that branch-folder does not create a fallthrough to a landing pad.
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+# Also make sure that the landing pad still can be tail merged.
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+---
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+name: foo
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+body: |
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+ ; CHECK-LABEL: name: foo
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+ bb.0:
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+ successors: %bb.1, %bb.3
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+ bb.1:
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+ JCC_1 %bb.4, 5, implicit killed $eflags
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+ bb.2:
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+ MOV8mi $r13, 1, $noreg, 0, $noreg, 0
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+ JMP_1 %bb.5
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+ ; CHECK: bb.2:
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+ ; CHECK-NOT: successors: {{.*}}bb.3
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+ ; CHECK: bb.3 (landing-pad):
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+ ; CHECK-NOT: MOV8mi
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+ bb.3(landing-pad):
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+ MOV8mi $r13, 1, $noreg, 0, $noreg, 0
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+ JMP_1 %bb.5
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+ ; CHECK: bb.4:
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+ bb.4:
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+ MOV8mi $r13, 2, $noreg, 0, $noreg, 0
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+ bb.5:
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+ RET 0
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+...
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--
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2.24.1.windows.2
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