[llvm-branch-commits] [llvm] release/22.x: [SimplifyCFG] process prof data when remove case in umin (#182261) (PR #185375)

[via llvm-branch-commits]

https://github.com/llvmbot created https://github.com/llvm/llvm-project/pull/185375

Backport 31e5f86a3cdc960ef7b2f0a533c4a37cf526cacd

Requested by: @nikic

>From f463bef09be73ae9a415fcd3fd49689bd95b0f0a Mon Sep 17 00:00:00 2001
From: Congcong Cai <congcongcai0907 at 163.com>
Date: Fri, 20 Feb 2026 07:03:27 +0800
Subject: [PATCH] [SimplifyCFG] process prof data when remove case in umin
 (#182261)

In #164097, we introduce a optimization for umin. But it does not handle
profile data correctly.
This PR remove profile data when remove cases.
Fixed: #181837

(cherry picked from commit 31e5f86a3cdc960ef7b2f0a533c4a37cf526cacd)
---
 llvm/lib/Transforms/Utils/SimplifyCFG.cpp     |  2 +-
 .../Transforms/SimplifyCFG/switch-umin.ll     | 43 +++++++++++++++++++
 2 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index 5f4807242581d..a16f274a4ed5a 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -7724,7 +7724,7 @@ static bool simplifySwitchWhenUMin(SwitchInst *SI, DomTreeUpdater *DTU) {
     BasicBlock *DeadCaseBB = I->getCaseSuccessor();
     DeadCaseBB->removePredecessor(BB);
     Updates.push_back({DominatorTree::Delete, BB, DeadCaseBB});
-    I = SIW->removeCase(I);
+    I = SIW.removeCase(I);
     E = SIW->case_end();
   }
 
diff --git a/llvm/test/Transforms/SimplifyCFG/switch-umin.ll b/llvm/test/Transforms/SimplifyCFG/switch-umin.ll
index 44665365dc222..ff958e4d04147 100644
--- a/llvm/test/Transforms/SimplifyCFG/switch-umin.ll
+++ b/llvm/test/Transforms/SimplifyCFG/switch-umin.ll
@@ -239,8 +239,51 @@ case4:
 
 }
 
+define void @switch_remove_dead_cases(i32 %x) {
+; CHECK-LABEL: define void @switch_remove_dead_cases(
+; CHECK-SAME: i32 [[X:%.*]]) {
+; CHECK-NEXT:    [[MIN:%.*]] = call i32 @llvm.umin.i32(i32 [[X]], i32 4)
+; CHECK-NEXT:    switch i32 [[X]], label %[[COMMON_RET:.*]] [
+; CHECK-NEXT:      i32 2, label %[[CASE_A:.*]]
+; CHECK-NEXT:      i32 3, label %[[CASE_B:.*]]
+; CHECK-NEXT:    ], !prof [[PROF1:![0-9]+]]
+; CHECK:       [[COMMON_RET]]:
+; CHECK-NEXT:    ret void
+; CHECK:       [[CASE_A]]:
+; CHECK-NEXT:    call void @a()
+; CHECK-NEXT:    br label %[[COMMON_RET]]
+; CHECK:       [[CASE_B]]:
+; CHECK-NEXT:    call void @b()
+; CHECK-NEXT:    br label %[[COMMON_RET]]
+;
+  %min = call i32 @llvm.umin.i32(i32 %x, i32 4)
+  switch i32 %min, label %unreachable [
+  i32 2, label %case_a
+  i32 3, label %case_b
+  i32 4, label %case_ret
+  i32 5, label %case_ret
+  ], !prof !1
+
+case_a:
+  call void @a()
+  ret void
+
+case_b:
+  call void @b()
+  ret void
+
+case_ret:
+  ret void
+
+unreachable:
+  unreachable
+}
 
 !0 = !{!"branch_weights", i32 1, i32 2, i32 3, i32 99, i32 5}
 ;.
 ; CHECK: [[PROF0]] = !{!"branch_weights", i32 5, i32 2, i32 3, i32 99}
 ;.
+!1 = !{!"branch_weights", i32 11, i32 12, i32 13, i32 14, i32 15}
+;.
+; CHECK: [[PROF1]] = !{!"branch_weights", i32 14, i32 12, i32 13}
+;.