[llvm] [XRay] Only avoid outlining pseudo-instructions, not whole blocks (PR #76520)
Daniel Hoekwater via llvm-commits
llvm-commits at lists.llvm.org
Thu Dec 28 10:02:08 PST 2023
https://github.com/dhoekwater created https://github.com/llvm/llvm-project/pull/76520
While some pseudo-instructions, such as fentry and PATCHABLE
instructions, must not be outlined, safe instruction sequences
within the same basic block can be outlined. Move the logic that
prevents pseudo-instruction outlining from the basic block level
to the instruction level. Doing so allows more instructions to be
safely outlined.
>From 50406b6c28403a2e2a5863c229861e105006757b Mon Sep 17 00:00:00 2001
From: Daniel Hoekwater <hoekwater at google.com>
Date: Wed, 26 Jul 2023 18:09:46 +0000
Subject: [PATCH] [XRay] Only avoid outlining pseudo-instructions, not whole
blocks
While some pseudo-instructions, such as fentry and PATCHABLE
instructions, must not be outlined, safe instruction sequences
within the same basic block can be outlined. Move the logic that
prevents pseudo-instruction outlining from the basic block level
to the instruction level. Doing so allows more instructions to be
safely outlined.
---
llvm/include/llvm/CodeGen/TargetInstrInfo.h | 4 +-
llvm/lib/CodeGen/TargetInstrInfo.cpp | 38 ++++----------
.../AArch64/machine-outliner-patchable.mir | 52 +++++++++----------
.../RISCV/machine-outliner-patchable.ll | 17 ++++--
4 files changed, 51 insertions(+), 60 deletions(-)
diff --git a/llvm/include/llvm/CodeGen/TargetInstrInfo.h b/llvm/include/llvm/CodeGen/TargetInstrInfo.h
index a113100f04e621..dc848b92ae681a 100644
--- a/llvm/include/llvm/CodeGen/TargetInstrInfo.h
+++ b/llvm/include/llvm/CodeGen/TargetInstrInfo.h
@@ -2081,7 +2081,9 @@ class TargetInstrInfo : public MCInstrInfo {
/// Optional target hook that returns true if \p MBB is safe to outline from,
/// and returns any target-specific information in \p Flags.
virtual bool isMBBSafeToOutlineFrom(MachineBasicBlock &MBB,
- unsigned &Flags) const;
+ unsigned &Flags) const {
+ return true;
+ }
/// Optional target hook which partitions \p MBB into outlinable ranges for
/// instruction mapping purposes. Each range is defined by two iterators:
diff --git a/llvm/lib/CodeGen/TargetInstrInfo.cpp b/llvm/lib/CodeGen/TargetInstrInfo.cpp
index 4783742a14ad7d..ecfa8df038b1a1 100644
--- a/llvm/lib/CodeGen/TargetInstrInfo.cpp
+++ b/llvm/lib/CodeGen/TargetInstrInfo.cpp
@@ -1778,6 +1778,16 @@ outliner::InstrType TargetInstrInfo::getOutliningType(
case TargetOpcode::LIFETIME_START:
case TargetOpcode::LIFETIME_END:
return outliner::InstrType::Invisible;
+
+ // Pseudo-instructions that must not be outlined
+ case TargetOpcode::FENTRY_CALL:
+ case TargetOpcode::PATCHABLE_FUNCTION_ENTER:
+ case TargetOpcode::PATCHABLE_FUNCTION_EXIT:
+ case TargetOpcode::PATCHABLE_EVENT_CALL:
+ case TargetOpcode::PATCHABLE_TYPED_EVENT_CALL:
+ case TargetOpcode::PATCHABLE_RET:
+ case TargetOpcode::PATCHABLE_TAIL_CALL:
+ return outliner::InstrType::Illegal;
default:
break;
}
@@ -1825,31 +1835,3 @@ outliner::InstrType TargetInstrInfo::getOutliningType(
// If we don't know, delegate to the target-specific hook.
return getOutliningTypeImpl(MIT, Flags);
}
-
-bool TargetInstrInfo::isMBBSafeToOutlineFrom(MachineBasicBlock &MBB,
- unsigned &Flags) const {
- // Some instrumentations create special TargetOpcode at the start which
- // expands to special code sequences which must be present.
- auto First = MBB.getFirstNonDebugInstr();
- if (First == MBB.end())
- return true;
-
- if (First->getOpcode() == TargetOpcode::FENTRY_CALL ||
- First->getOpcode() == TargetOpcode::PATCHABLE_FUNCTION_ENTER)
- return false;
-
- // Some instrumentations create special pseudo-instructions at or just before
- // the end that must be present.
- auto Last = MBB.getLastNonDebugInstr();
- if (Last->getOpcode() == TargetOpcode::PATCHABLE_RET ||
- Last->getOpcode() == TargetOpcode::PATCHABLE_TAIL_CALL)
- return false;
-
- if (Last != First && Last->isReturn()) {
- --Last;
- if (Last->getOpcode() == TargetOpcode::PATCHABLE_FUNCTION_EXIT ||
- Last->getOpcode() == TargetOpcode::PATCHABLE_TAIL_CALL)
- return false;
- }
- return true;
-}
diff --git a/llvm/test/CodeGen/AArch64/machine-outliner-patchable.mir b/llvm/test/CodeGen/AArch64/machine-outliner-patchable.mir
index 6e957bceb8f4f8..c9c21faf4953f0 100644
--- a/llvm/test/CodeGen/AArch64/machine-outliner-patchable.mir
+++ b/llvm/test/CodeGen/AArch64/machine-outliner-patchable.mir
@@ -1,4 +1,5 @@
-# RUN: llc -mtriple=aarch64-none-linux-gnu -run-pass machine-outliner -verify-machineinstrs -enable-machine-outliner %s -o - | FileCheck %s
+# RUN: llc -mtriple=aarch64-none-linux-gnu -run-pass machine-outliner -verify-machineinstrs -enable-machine-outliner %s -o - | FileCheck %s -check-prefixes=CHECK,FUNCTION_A
+# RUN: llc -mtriple=aarch64-none-linux-gnu -run-pass machine-outliner -verify-machineinstrs -enable-machine-outliner %s -o - | FileCheck %s -check-prefixes=CHECK,FUNCTION_B
--- |
; Function Attrs: minsize
declare void @foo(i32, i32, i32, i32) #0
@@ -47,20 +48,16 @@ stack:
machineFunctionInfo:
hasRedZone: false
body: |
+ ; COM: Make sure that PATCHABLE_FUNCTION_ENTER and PATCHABLE_FUNCTION_EXIT
+ ; COM: instructions aren't outlined.
; CHECK-LABEL: name: xray0
; CHECK: bb.0.entry:
; CHECK: PATCHABLE_FUNCTION_ENTER
; CHECK: bb.1.if.then:
- ; CHECK: BL @[[OUTLINED_FUNCTION:OUTLINED_FUNCTION_[0-9]]]
+ ; CHECK: BL @[[OUTLINED_FUNCTION_A:OUTLINED_FUNCTION_[0-9]]]
; CHECK: bb.2.if.end:
- ; CHECK-NEXT: $w0 = MOVZWi 5, 0
- ; CHECK-NEXT: $w1 = MOVZWi 6, 0
- ; CHECK-NEXT: $w2 = MOVZWi 7, 0
- ; CHECK-NEXT: $w3 = MOVZWi 8, 0
- ; CHECK-NEXT: BL @foo, csr_aarch64_aapcs, implicit-def dead $lr, implicit $sp, implicit killed $w0, implicit killed $w1, implicit killed $w2, implicit killed $w3, implicit-def $sp
- ; CHECK: $w0 = MOVZWi 5, 0
- ; CHECK-NEXT: $w1 = MOVZWi 6, 0
- ; CHECK-NEXT: PATCHABLE_FUNCTION_EXIT
+ ; CHECK: BL @[[OUTLINED_FUNCTION_B:OUTLINED_FUNCTION_[0-9]]]
+ ; CHECK: PATCHABLE_FUNCTION_EXIT
; CHECK-NEXT: RET undef $lr
bb.0.entry:
@@ -109,16 +106,10 @@ body: |
; CHECK: bb.0.entry:
; CHECK: PATCHABLE_FUNCTION_ENTER
; CHECK: bb.1.if.then:
- ; CHECK: BL @[[OUTLINED_FUNCTION]]
+ ; CHECK: BL @[[OUTLINED_FUNCTION_A]]
; CHECK: bb.2.if.end:
- ; CHECK-NEXT: $w0 = MOVZWi 5, 0
- ; CHECK-NEXT: $w1 = MOVZWi 6, 0
- ; CHECK-NEXT: $w2 = MOVZWi 7, 0
- ; CHECK-NEXT: $w3 = MOVZWi 8, 0
- ; CHECK-NEXT: BL @foo, csr_aarch64_aapcs, implicit-def dead $lr, implicit $sp, implicit killed $w0, implicit killed $w1, implicit killed $w2, implicit killed $w3, implicit-def $sp
- ; CHECK: $w0 = MOVZWi 5, 0
- ; CHECK-NEXT: $w1 = MOVZWi 6, 0
- ; CHECK-NEXT: PATCHABLE_FUNCTION_EXIT
+ ; CHECK: BL @[[OUTLINED_FUNCTION_B]]
+ ; CHECK: PATCHABLE_FUNCTION_EXIT
; CHECK-NEXT: RET undef $lr
bb.0.entry:
@@ -150,13 +141,20 @@ body: |
PATCHABLE_FUNCTION_EXIT
RET undef $lr
- ; CHECK: name: [[OUTLINED_FUNCTION]]
- ; CHECK: bb.0:
- ; CHECK: $w0 = MOVZWi 1, 0
- ; CHECK-NEXT: $w1 = MOVZWi 2, 0
- ; CHECK-NEXT: $w2 = MOVZWi 3, 0
- ; CHECK-NEXT: $w3 = MOVZWi 4, 0
- ; CHECK-NEXT: TCRETURNdi @foo, 0, implicit $sp
+ ; FUNCTION_A: name: [[OUTLINED_FUNCTION_A]]
+ ; FUNCTION_A: bb.0:
+ ; FUNCTION_A: $w0 = MOVZWi 1, 0
+ ; FUNCTION_A-NEXT: $w1 = MOVZWi 2, 0
+ ; FUNCTION_A-NEXT: $w2 = MOVZWi 3, 0
+ ; FUNCTION_A-NEXT: $w3 = MOVZWi 4, 0
+ ; FUNCTION_A-NEXT: TCRETURNdi @foo, 0, implicit $sp
-...
+ ; FUNCTION_B: name: [[OUTLINED_FUNCTION_B]]
+ ; FUNCTION_B: bb.0:
+ ; FUNCTION_B: $w0 = MOVZWi 5, 0
+ ; FUNCTION_B-NEXT: $w1 = MOVZWi 6, 0
+ ; FUNCTION_B-NEXT: $w2 = MOVZWi 7, 0
+ ; FUNCTION_B-NEXT: $w3 = MOVZWi 8, 0
+ ; FUNCTION_B-NEXT: TCRETURNdi @foo, 0, implicit $sp
+...
diff --git a/llvm/test/CodeGen/RISCV/machine-outliner-patchable.ll b/llvm/test/CodeGen/RISCV/machine-outliner-patchable.ll
index 4ef3abd241577f..1f3930154a494a 100644
--- a/llvm/test/CodeGen/RISCV/machine-outliner-patchable.ll
+++ b/llvm/test/CodeGen/RISCV/machine-outliner-patchable.ll
@@ -11,7 +11,7 @@ define void @fentry0(i1 %a) nounwind "fentry-call"="true" {
; CHECK-NEXT: # %bb.0:
; CHECK-NEXT: # FEntry call
; CHECK: # %bb.1:
-; CHECK-NEXT: call t0, OUTLINED_FUNCTION_1
+; CHECK-NEXT: call t0, [[OUTLINED_FUNCTION:OUTLINED_FUNCTION_[0-9]+]]
entry:
br i1 %a, label %if.then, label %if.end
if.then:
@@ -27,7 +27,7 @@ define void @fentry1(i1 %a) nounwind "fentry-call"="true" {
; CHECK-NEXT: # %bb.0:
; CHECK-NEXT: # FEntry call
; CHECK: # %bb.1:
-; CHECK-NEXT: call t0, OUTLINED_FUNCTION_1
+; CHECK-NEXT: call t0, [[OUTLINED_FUNCTION]]
entry:
br i1 %a, label %if.then, label %if.end
if.then:
@@ -47,7 +47,7 @@ define void @patchable0(i1 %a) nounwind "patchable-function-entry"="2" {
; CHECK-NEXT: nop
; CHECK-NEXT: nop
; CHECK: # %bb.1:
-; CHECK-NEXT: call t0, OUTLINED_FUNCTION_1
+; CHECK-NEXT: call t0, [[OUTLINED_FUNCTION]]
entry:
br i1 %a, label %if.then, label %if.end
if.then:
@@ -65,7 +65,7 @@ define void @patchable1(i1 %a) nounwind "patchable-function-entry"="2" {
; CHECK-NEXT: nop
; CHECK-NEXT: nop
; CHECK: # %bb.1:
-; CHECK-NEXT: call t0, OUTLINED_FUNCTION_1
+; CHECK-NEXT: call t0, [[OUTLINED_FUNCTION]]
entry:
br i1 %a, label %if.then, label %if.end
if.then:
@@ -75,3 +75,12 @@ if.end:
call void @foo(i32 5, i32 6, i32 7, i32 8)
ret void
}
+
+;; Make sure that OUTLINED_FUNCTION contains the right instructions
+; CHECK: [[OUTLINED_FUNCTION]]:
+; CHECK-NEXT: # %bb.0:
+; CHECK-NEXT: li a0, 1
+; CHECK-NEXT: li a1, 2
+; CHECK-NEXT: li a2, 3
+; CHECK-NEXT: li a3, 4
+; CHECK-NEXT: jr t0
\ No newline at end of file
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