[llvm] [CodeGen] Use temp symbol for MBBs (PR #95031)
Alexis Engelke via llvm-commits
llvm-commits at lists.llvm.org
Thu Jun 20 04:17:56 PDT 2024
https://github.com/aengelke updated https://github.com/llvm/llvm-project/pull/95031
>From 1882f7d13cd356f5086f80bdb9e93a9c3b505964 Mon Sep 17 00:00:00 2001
From: Alexis Engelke <engelke at in.tum.de>
Date: Mon, 10 Jun 2024 20:29:09 +0200
Subject: [PATCH 1/2] [CodeGen] Use temporary symbol for MBBs
Internal label names never occur in the symbol table, so when using an
object streamer, there's no point in constructing these names and then
adding them to hash tables -- they are never visible in the output.
It's not possible to reuse createTempSymbol, because on BPF has a
different prefix for globals and basic blocks right now.
---
llvm/include/llvm/MC/MCContext.h | 6 ++++++
llvm/lib/CodeGen/MachineBasicBlock.cpp | 16 ++++++++--------
llvm/lib/MC/MCContext.cpp | 12 ++++++++++++
.../AArch64/branch-relax-cross-section.mir | 4 ++--
llvm/test/CodeGen/BPF/objdump_cond_op.ll | 9 +++------
llvm/test/CodeGen/BPF/objdump_cond_op_2.ll | 6 ++----
6 files changed, 33 insertions(+), 20 deletions(-)
diff --git a/llvm/include/llvm/MC/MCContext.h b/llvm/include/llvm/MC/MCContext.h
index e32a5321bc2a0..6c977a5bc0f1f 100644
--- a/llvm/include/llvm/MC/MCContext.h
+++ b/llvm/include/llvm/MC/MCContext.h
@@ -455,6 +455,12 @@ class MCContext {
MCSymbol *createNamedTempSymbol();
MCSymbol *createNamedTempSymbol(const Twine &Name);
+ /// Get or create a symbol for a basic block. For non-always-emit symbols,
+ /// this behaves like createTempSymbol, except that it uses the
+ /// PrivateLabelPrefix instead of the PrivateGlobalPrefix. When AlwaysEmit is
+ /// true, behaves like getOrCreateSymbol, prefixed with PrivateLabelPrefix.
+ MCSymbol *createBlockSymbol(const Twine &Name, bool AlwaysEmit = false);
+
/// Create the definition of a directional local symbol for numbered label
/// (used for "1:" definitions).
MCSymbol *createDirectionalLocalSymbol(unsigned LocalLabelVal);
diff --git a/llvm/lib/CodeGen/MachineBasicBlock.cpp b/llvm/lib/CodeGen/MachineBasicBlock.cpp
index 16505f21f0aad..abf43e39ee9a6 100644
--- a/llvm/lib/CodeGen/MachineBasicBlock.cpp
+++ b/llvm/lib/CodeGen/MachineBasicBlock.cpp
@@ -80,10 +80,11 @@ MCSymbol *MachineBasicBlock::getSymbol() const {
}
CachedMCSymbol = Ctx.getOrCreateSymbol(MF->getName() + Suffix);
} else {
- const StringRef Prefix = Ctx.getAsmInfo()->getPrivateLabelPrefix();
- CachedMCSymbol = Ctx.getOrCreateSymbol(Twine(Prefix) + "BB" +
- Twine(MF->getFunctionNumber()) +
- "_" + Twine(getNumber()));
+ // If the block occurs as label in inline assembly, parsing the assembly
+ // needs an actual label name => set AlwaysEmit in these cases.
+ CachedMCSymbol = Ctx.createBlockSymbol(
+ "BB" + Twine(MF->getFunctionNumber()) + "_" + Twine(getNumber()),
+ /*AlwaysEmit=*/hasLabelMustBeEmitted());
}
}
return CachedMCSymbol;
@@ -104,10 +105,9 @@ MCSymbol *MachineBasicBlock::getEndSymbol() const {
if (!CachedEndMCSymbol) {
const MachineFunction *MF = getParent();
MCContext &Ctx = MF->getContext();
- auto Prefix = Ctx.getAsmInfo()->getPrivateLabelPrefix();
- CachedEndMCSymbol = Ctx.getOrCreateSymbol(Twine(Prefix) + "BB_END" +
- Twine(MF->getFunctionNumber()) +
- "_" + Twine(getNumber()));
+ CachedEndMCSymbol = Ctx.createBlockSymbol(
+ "BB_END" + Twine(MF->getFunctionNumber()) + "_" + Twine(getNumber()),
+ /*AlwaysEmit=*/false);
}
return CachedEndMCSymbol;
}
diff --git a/llvm/lib/MC/MCContext.cpp b/llvm/lib/MC/MCContext.cpp
index 9c7cb74e8533c..a490997e5438e 100644
--- a/llvm/lib/MC/MCContext.cpp
+++ b/llvm/lib/MC/MCContext.cpp
@@ -318,6 +318,18 @@ MCSymbol *MCContext::createNamedTempSymbol(const Twine &Name) {
/*IsTemporary=*/!SaveTempLabels);
}
+MCSymbol *MCContext::createBlockSymbol(const Twine &Name, bool AlwaysEmit) {
+ if (AlwaysEmit)
+ return getOrCreateSymbol(MAI->getPrivateLabelPrefix() + Name);
+
+ if (!UseNamesOnTempLabels)
+ return createSymbolImpl(nullptr, /*IsTemporary=*/true);
+
+ SmallString<128> NameSV;
+ raw_svector_ostream(NameSV) << MAI->getPrivateLabelPrefix() << Name;
+ return createSymbol(NameSV, false, /*IsTemporary=*/true);
+}
+
MCSymbol *MCContext::createLinkerPrivateTempSymbol() {
return createLinkerPrivateSymbol("tmp");
}
diff --git a/llvm/test/CodeGen/AArch64/branch-relax-cross-section.mir b/llvm/test/CodeGen/AArch64/branch-relax-cross-section.mir
index f8f0b76f1c9ff..db88bf0044a5f 100644
--- a/llvm/test/CodeGen/AArch64/branch-relax-cross-section.mir
+++ b/llvm/test/CodeGen/AArch64/branch-relax-cross-section.mir
@@ -473,8 +473,8 @@ body: |
; INDIRECT-NEXT: successors: %bb.1
; INDIRECT-NEXT: liveins: $x16
; INDIRECT-NEXT: {{ $}}
- ; INDIRECT-NEXT: $[[SCAVENGED_REGISTER:x[0-9]+]] = ADRP target-flags(aarch64-page) <mcsymbol .LBB5_1>
- ; INDIRECT-NEXT: $[[SCAVENGED_REGISTER]] = ADDXri $[[SCAVENGED_REGISTER]], target-flags(aarch64-pageoff, aarch64-nc) <mcsymbol .LBB5_1>, 0
+ ; INDIRECT-NEXT: $[[SCAVENGED_REGISTER:x[0-9]+]] = ADRP target-flags(aarch64-page) <mcsymbol >
+ ; INDIRECT-NEXT: $[[SCAVENGED_REGISTER]] = ADDXri $[[SCAVENGED_REGISTER]], target-flags(aarch64-pageoff, aarch64-nc) <mcsymbol >, 0
; INDIRECT-NEXT: BR $[[SCAVENGED_REGISTER]]
bb.0.entry:
diff --git a/llvm/test/CodeGen/BPF/objdump_cond_op.ll b/llvm/test/CodeGen/BPF/objdump_cond_op.ll
index 4a4fa84376cc8..3b2e6c1922fc4 100644
--- a/llvm/test/CodeGen/BPF/objdump_cond_op.ll
+++ b/llvm/test/CodeGen/BPF/objdump_cond_op.ll
@@ -27,7 +27,7 @@ define i32 @test(i32, i32) local_unnamed_addr #0 {
br label %13
; CHECK: r1 <<= 32
; CHECK: r1 >>= 32
-; CHECK: if r1 != 2 goto +6 <LBB0_2>
+; CHECK: if r1 != 2 goto +6 <test+0x48>
; <label>:8: ; preds = %2
%9 = icmp eq i32 %0, %1
@@ -38,32 +38,29 @@ define i32 @test(i32, i32) local_unnamed_addr #0 {
; CHECK: r0 = *(u32 *)(r1 + 0)
; CHECK: r0 *= r0
; CHECK: r0 <<= 1
-; CHECK: goto +7 <LBB0_4>
+; CHECK: goto +7 <test+0x80>
; <label>:11: ; preds = %8
%12 = shl nsw i32 %10, 2
br label %13
-; CHECK-LABEL: <LBB0_2>:
; CHECK: r3 = 0 ll
; CHECK: r0 = *(u32 *)(r3 + 0)
; CHECK: r2 <<= 32
; CHECK: r2 >>= 32
-; CHECK: if r1 == r2 goto +4 <LBB0_5>
+; CHECK: if r1 == r2 goto +4 <test+0x98>
; CHECK: r0 <<= 2
; <label>:13: ; preds = %4, %11
%14 = phi i32 [ %12, %11 ], [ %7, %4 ]
store i32 %14, ptr @gbl, align 4
br label %15
-; CHECK-LABEL: <LBB0_4>:
; CHECK: r1 = 0 ll
; CHECK: *(u32 *)(r1 + 0) = r0
; <label>:15: ; preds = %8, %13
%16 = phi i32 [ %14, %13 ], [ %10, %8 ]
ret i32 %16
-; CHECK-LABEL: <LBB0_5>:
; CHECK: exit
}
attributes #0 = { norecurse nounwind }
diff --git a/llvm/test/CodeGen/BPF/objdump_cond_op_2.ll b/llvm/test/CodeGen/BPF/objdump_cond_op_2.ll
index 4edd52a463ea9..8c9e91d4a80ea 100644
--- a/llvm/test/CodeGen/BPF/objdump_cond_op_2.ll
+++ b/llvm/test/CodeGen/BPF/objdump_cond_op_2.ll
@@ -14,8 +14,7 @@ define i32 @test(i32, i32) local_unnamed_addr #0 {
; <label>:4: ; preds = %2
br label %5
-; CHECK: if r4 s>= r3 goto +10 <LBB0_2>
-; CHECK-LABEL: <LBB0_1>:
+; CHECK: if r4 s>= r3 goto +10 <test+0x90>
; <label>:5: ; preds = %4, %5
%6 = phi i32 [ %9, %5 ], [ 0, %4 ]
@@ -27,12 +26,11 @@ define i32 @test(i32, i32) local_unnamed_addr #0 {
%12 = icmp slt i32 %10, %11
br i1 %12, label %5, label %13
; CHECK: r1 = r3
-; CHECK: if r2 s> r3 goto -10 <LBB0_1>
+; CHECK: if r2 s> r3 goto -10 <test+0x40>
; <label>:13: ; preds = %5, %2
%14 = phi i32 [ 0, %2 ], [ %9, %5 ]
ret i32 %14
-; CHECK-LABEL: <LBB0_2>:
; CHECK: exit
}
attributes #0 = { norecurse nounwind readnone }
>From 495ef5972bbcc2e83b33fa9b19f75955199226d8 Mon Sep 17 00:00:00 2001
From: Alexis Engelke <engelke at in.tum.de>
Date: Thu, 20 Jun 2024 11:04:57 +0000
Subject: [PATCH 2/2] rebase
---
llvm/lib/MC/MCContext.cpp | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)
diff --git a/llvm/lib/MC/MCContext.cpp b/llvm/lib/MC/MCContext.cpp
index a490997e5438e..729e8daea6408 100644
--- a/llvm/lib/MC/MCContext.cpp
+++ b/llvm/lib/MC/MCContext.cpp
@@ -322,12 +322,11 @@ MCSymbol *MCContext::createBlockSymbol(const Twine &Name, bool AlwaysEmit) {
if (AlwaysEmit)
return getOrCreateSymbol(MAI->getPrivateLabelPrefix() + Name);
- if (!UseNamesOnTempLabels)
- return createSymbolImpl(nullptr, /*IsTemporary=*/true);
-
- SmallString<128> NameSV;
- raw_svector_ostream(NameSV) << MAI->getPrivateLabelPrefix() << Name;
- return createSymbol(NameSV, false, /*IsTemporary=*/true);
+ bool IsTemporary = !SaveTempLabels;
+ if (IsTemporary && !UseNamesOnTempLabels)
+ return createSymbolImpl(nullptr, IsTemporary);
+ return createRenamableSymbol(MAI->getPrivateLabelPrefix() << Name,
+ /*AlwaysAddSuffix=*/false, IsTemporary);
}
MCSymbol *MCContext::createLinkerPrivateTempSymbol() {
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