[llvm] [LoongArch] Enable LoopTermFold Pass (PR #130737)

[via llvm-commits]

https://github.com/tangaac created https://github.com/llvm/llvm-project/pull/130737

None

>From 4ec9f438e3ebf377cb611fcf7b5f4eeaea7f1288 Mon Sep 17 00:00:00 2001
From: tangaac <tangyan01 at loongson.cn>
Date: Tue, 11 Mar 2025 17:00:12 +0800
Subject: [PATCH] Enable LoopTermFold Pass

---
 .../LoongArch/LoongArchTargetMachine.cpp      |  4 +-
 llvm/test/CodeGen/LoongArch/opt-pipeline.ll   |  1 +
 .../CodeGen/LoongArch/preferred-alignments.ll |  6 +--
 .../LoongArch/lit.local.cfg                   |  2 +
 .../LoongArch/term-fold-crash.ll              | 43 +++++++++++++++++++
 5 files changed, 52 insertions(+), 4 deletions(-)
 create mode 100644 llvm/test/Transforms/LoopStrengthReduce/LoongArch/lit.local.cfg
 create mode 100644 llvm/test/Transforms/LoopStrengthReduce/LoongArch/term-fold-crash.ll

diff --git a/llvm/lib/Target/LoongArch/LoongArchTargetMachine.cpp b/llvm/lib/Target/LoongArch/LoongArchTargetMachine.cpp
index 62b08be5435cd..53b884563ad88 100644
--- a/llvm/lib/Target/LoongArch/LoongArchTargetMachine.cpp
+++ b/llvm/lib/Target/LoongArch/LoongArchTargetMachine.cpp
@@ -146,7 +146,9 @@ namespace {
 class LoongArchPassConfig : public TargetPassConfig {
 public:
   LoongArchPassConfig(LoongArchTargetMachine &TM, PassManagerBase &PM)
-      : TargetPassConfig(TM, PM) {}
+      : TargetPassConfig(TM, PM) {
+    EnableLoopTermFold = true;
+  }
 
   LoongArchTargetMachine &getLoongArchTargetMachine() const {
     return getTM<LoongArchTargetMachine>();
diff --git a/llvm/test/CodeGen/LoongArch/opt-pipeline.ll b/llvm/test/CodeGen/LoongArch/opt-pipeline.ll
index ab76d4e998d2b..c6c1c124c8314 100644
--- a/llvm/test/CodeGen/LoongArch/opt-pipeline.ll
+++ b/llvm/test/CodeGen/LoongArch/opt-pipeline.ll
@@ -44,6 +44,7 @@
 ; LAXX-NEXT:         Canonicalize Freeze Instructions in Loops
 ; LAXX-NEXT:         Induction Variable Users
 ; LAXX-NEXT:         Loop Strength Reduction
+; LAXX-NEXT:         Loop Terminator Folding
 ; LAXX-NEXT:       Basic Alias Analysis (stateless AA impl)
 ; LAXX-NEXT:       Function Alias Analysis Results
 ; LAXX-NEXT:       Merge contiguous icmps into a memcmp
diff --git a/llvm/test/CodeGen/LoongArch/preferred-alignments.ll b/llvm/test/CodeGen/LoongArch/preferred-alignments.ll
index c3618db646016..2e12d7ed9d13f 100644
--- a/llvm/test/CodeGen/LoongArch/preferred-alignments.ll
+++ b/llvm/test/CodeGen/LoongArch/preferred-alignments.ll
@@ -10,13 +10,13 @@ define signext i32 @sum(ptr noalias nocapture noundef readonly %0, i32 noundef s
 ; LA464-NEXT:  # %bb.1:
 ; LA464-NEXT:    move $a2, $zero
 ; LA464-NEXT:    bstrpick.d $a1, $a1, 31, 0
+; LA464-NEXT:    alsl.d $a1, $a1, $a0, 2
 ; LA464-NEXT:    .p2align 4, , 16
 ; LA464-NEXT:  .LBB0_2: # =>This Inner Loop Header: Depth=1
 ; LA464-NEXT:    ld.w $a3, $a0, 0
-; LA464-NEXT:    add.w $a2, $a3, $a2
-; LA464-NEXT:    addi.d $a1, $a1, -1
 ; LA464-NEXT:    addi.d $a0, $a0, 4
-; LA464-NEXT:    bnez $a1, .LBB0_2
+; LA464-NEXT:    add.w $a2, $a3, $a2
+; LA464-NEXT:    bne $a0, $a1, .LBB0_2
 ; LA464-NEXT:  # %bb.3:
 ; LA464-NEXT:    move $a0, $a2
 ; LA464-NEXT:    ret
diff --git a/llvm/test/Transforms/LoopStrengthReduce/LoongArch/lit.local.cfg b/llvm/test/Transforms/LoopStrengthReduce/LoongArch/lit.local.cfg
new file mode 100644
index 0000000000000..cc24278acbb41
--- /dev/null
+++ b/llvm/test/Transforms/LoopStrengthReduce/LoongArch/lit.local.cfg
@@ -0,0 +1,2 @@
+if not "LoongArch" in config.root.targets:
+    config.unsupported = True
diff --git a/llvm/test/Transforms/LoopStrengthReduce/LoongArch/term-fold-crash.ll b/llvm/test/Transforms/LoopStrengthReduce/LoongArch/term-fold-crash.ll
new file mode 100644
index 0000000000000..54fe262aca941
--- /dev/null
+++ b/llvm/test/Transforms/LoopStrengthReduce/LoongArch/term-fold-crash.ll
@@ -0,0 +1,43 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -S -passes=loop-reduce,loop-term-fold -mtriple=loongarch64 < %s | FileCheck %s
+
+define void @test(ptr %p, i8 %arg, i32 %start) {
+; CHECK-LABEL: define void @test(
+; CHECK-SAME: ptr [[P:%.*]], i8 [[ARG:%.*]], i32 [[START:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    [[CONV:%.*]] = zext i8 [[ARG]] to i32
+; CHECK-NEXT:    [[SHR:%.*]] = lshr i32 [[CONV]], 1
+; CHECK-NEXT:    [[TMP0:%.*]] = add i32 [[START]], [[SHR]]
+; CHECK-NEXT:    [[TMP1:%.*]] = add i32 [[TMP0]], 1
+; CHECK-NEXT:    br label %[[FOR_BODY:.*]]
+; CHECK:       [[FOR_BODY]]:
+; CHECK-NEXT:    [[ADD810:%.*]] = phi i32 [ [[START]], %[[ENTRY]] ], [ [[ADD:%.*]], %[[FOR_BODY]] ]
+; CHECK-NEXT:    [[IDXPROM2:%.*]] = zext i32 [[ADD810]] to i64
+; CHECK-NEXT:    [[ARRAYIDX3:%.*]] = getelementptr i8, ptr [[P]], i64 [[IDXPROM2]]
+; CHECK-NEXT:    [[V:%.*]] = load i8, ptr [[ARRAYIDX3]], align 1
+; CHECK-NEXT:    [[ADD]] = add i32 [[ADD810]], 1
+; CHECK-NEXT:    [[LSR_FOLD_TERM_COND_REPLACED_TERM_COND:%.*]] = icmp eq i32 [[ADD]], [[TMP1]]
+; CHECK-NEXT:    br i1 [[LSR_FOLD_TERM_COND_REPLACED_TERM_COND]], label %[[EXIT:.*]], label %[[FOR_BODY]]
+; CHECK:       [[EXIT]]:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %conv = zext i8 %arg to i32
+  %shr = lshr i32 %conv, 1
+  %wide.trip.count = zext nneg i32 %shr to i64
+  br label %for.body
+
+for.body:
+  %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
+  %add810 = phi i32 [ %start, %entry ], [ %add, %for.body ]
+  %idxprom2 = zext i32 %add810 to i64
+  %arrayidx3 = getelementptr i8, ptr %p, i64 %idxprom2
+  %v = load i8, ptr %arrayidx3, align 1
+  %add = add i32 %add810, 1
+  %indvars.iv.next = add i64 %indvars.iv, 1
+  %exitcond.not = icmp eq i64 %indvars.iv, %wide.trip.count
+  br i1 %exitcond.not, label %exit, label %for.body
+
+exit:
+  ret void
+}