[llvm] [MachineLoopInfo] Fix getLoopID to handle multi latches. (PR #106195)
Freddy Ye via llvm-commits
llvm-commits at lists.llvm.org
Tue Aug 27 00:35:22 PDT 2024
https://github.com/FreddyLeaf created https://github.com/llvm/llvm-project/pull/106195
This patch also fixed CodegenPrepare to reserve loop metadata when merging blocks.
This fixes issue #102632
>From 0cf06aedfd07eb4be274407bcc99fa28798f55de Mon Sep 17 00:00:00 2001
From: Freddy Ye <freddy.ye at intel.com>
Date: Wed, 21 Aug 2024 11:12:57 +0800
Subject: [PATCH] [MachineLoopInfo] Fix getLoopID to handle multi latches.
This patch also fixed CodegenPrepare to reserve loop metadata
when merging blocks.
This fixes issue #102632
---
llvm/lib/CodeGen/CodeGenPrepare.cpp | 6 +++
llvm/lib/CodeGen/MachineLoopInfo.cpp | 2 -
llvm/test/CodeGen/X86/code-align-loops.ll | 50 +++++++++++++++++++++++
3 files changed, 56 insertions(+), 2 deletions(-)
diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index bf48c1fdab0ff0..c63a265fe27789 100644
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -1183,6 +1183,12 @@ void CodeGenPrepare::eliminateMostlyEmptyBlock(BasicBlock *BB) {
}
}
+ // Reserve loop Metadata.
+ if (BI->hasMetadata(LLVMContext::MD_loop)) {
+ for (auto *Pred : predecessors(BB))
+ Pred->getTerminator()->copyMetadata(*BI, LLVMContext::MD_loop);
+ }
+
// The PHIs are now updated, change everything that refers to BB to use
// DestBB and remove BB.
BB->replaceAllUsesWith(DestBB);
diff --git a/llvm/lib/CodeGen/MachineLoopInfo.cpp b/llvm/lib/CodeGen/MachineLoopInfo.cpp
index 88ba10fbe29a91..b82b41fac662d7 100644
--- a/llvm/lib/CodeGen/MachineLoopInfo.cpp
+++ b/llvm/lib/CodeGen/MachineLoopInfo.cpp
@@ -211,8 +211,6 @@ MDNode *MachineLoop::getLoopID() const {
break;
}
}
- if (!MD)
- return nullptr;
if (!LoopID)
LoopID = MD;
else if (MD != LoopID)
diff --git a/llvm/test/CodeGen/X86/code-align-loops.ll b/llvm/test/CodeGen/X86/code-align-loops.ll
index 3823293d747c7d..40ad3b4c8d600e 100644
--- a/llvm/test/CodeGen/X86/code-align-loops.ll
+++ b/llvm/test/CodeGen/X86/code-align-loops.ll
@@ -96,6 +96,56 @@ for.body5: ; preds = %for.body, %for.body
br i1 %exitcond16.not, label %for.cond.cleanup4, label %for.body5, !llvm.loop !2
}
+; test3 is to check if .p2align can be correctly set on loops with multi latches.
+; The test IR is generated from below simple C file:
+; $ clang -O0 -S -emit-llvm loop.c
+; $ cat loop.c
+; int test3() {
+; int i = 0;
+; [[clang::code_align(32)]]
+; while (i < 10) {
+; if (i % 2) {
+; continue;
+; }
+; i++;
+; }
+; }
+; CHECK-LABEL: test3_multilatch:
+; ALIGN: .p2align 6, 0x90
+; ALIGN-NEXT: .LBB2_1: # %while.cond
+define dso_local i32 @test3_multilatch() #0 {
+entry:
+ %retval = alloca i32, align 4
+ %i = alloca i32, align 4
+ store i32 0, ptr %retval, align 4
+ store i32 0, ptr %i, align 4
+ br label %while.cond
+
+while.cond: ; preds = %if.end, %if.then, %entry
+ %0 = load i32, ptr %i, align 4
+ %cmp = icmp slt i32 %0, 10
+ br i1 %cmp, label %while.body, label %while.end
+
+while.body: ; preds = %while.cond
+ %1 = load i32, ptr %i, align 4
+ %rem = srem i32 %1, 2
+ %tobool = icmp ne i32 %rem, 0
+ br i1 %tobool, label %if.then, label %if.end
+
+if.then: ; preds = %while.body
+ br label %while.cond, !llvm.loop !0
+
+if.end: ; preds = %while.body
+ %2 = load i32, ptr %i, align 4
+ %inc = add nsw i32 %2, 1
+ store i32 %inc, ptr %i, align 4
+ br label %while.cond, !llvm.loop !0
+
+while.end: ; preds = %while.cond
+ %3 = load i32, ptr %retval, align 4
+ ret i32 %3
+}
+
declare void @bar()
declare void @var()
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