From 55759afdd1874fa5d9d97d6042a864b88d60526f Mon Sep 17 00:00:00 2001
From: Leon Shen <leon@yhls.org>
Date: Mon, 23 Sep 2019 18:21:55 -0400
Subject: [PATCH] fix bug related to block renaming for DCE

---
 base/compiler/ssair/ir.jl |  4 ++--
 test/compiler/ssair.jl    | 31 +++++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/base/compiler/ssair/ir.jl b/base/compiler/ssair/ir.jl
index 0aec26d444476..665387c1143b6 100644
--- a/base/compiler/ssair/ir.jl
+++ b/base/compiler/ssair/ir.jl
@@ -1001,14 +1001,14 @@ end
 
 function finish_current_bb!(compact, active_bb, old_result_idx=compact.result_idx, unreachable=false)
     if compact.active_result_bb > length(compact.result_bbs)
-        #@assert compact.bb_rename[active_bb] == 0
+        #@assert compact.bb_rename[active_bb] == -1
         return true
     end
     bb = compact.result_bbs[compact.active_result_bb]
     # If this was the last statement in the BB and we decided to skip it, insert a
     # dummy `nothing` node, to prevent changing the structure of the CFG
     skipped = false
-    if !compact.cfg_transforms_enabled || active_bb == 0 || active_bb > length(compact.bb_rename_succ) || compact.bb_rename_succ[active_bb] != 0
+    if !compact.cfg_transforms_enabled || active_bb == 0 || active_bb > length(compact.bb_rename_succ) || compact.bb_rename_succ[active_bb] != -1
         if compact.result_idx == first(bb.stmts)
             length(compact.result) < old_result_idx && resize!(compact, old_result_idx)
             if unreachable
diff --git a/test/compiler/ssair.jl b/test/compiler/ssair.jl
index 30f53b124ed66..116e099398b7b 100644
--- a/test/compiler/ssair.jl
+++ b/test/compiler/ssair.jl
@@ -132,3 +132,34 @@ function f32579(x::Int, b::Bool)
 end
 @test f32579(0, true) === true
 @test f32579(0, false) === false
+
+# Test for bug caused by renaming blocks improperly, related to PR #32145
+using Base.Meta
+let ci = (Meta.@lower 1 + 1).args[1]
+    ci.code = [
+        # block 1
+        Core.Compiler.GotoIfNot(Expr(:boundscheck), 6),
+        # block 2
+        Expr(:call, GlobalRef(Base, :size), Core.Compiler.Argument(3)),
+        Core.Compiler.ReturnNode(),
+        # block 3
+        Core.PhiNode(),
+        Core.Compiler.ReturnNode(),
+        # block 4
+        Expr(:call,
+             GlobalRef(Main, :something),
+             GlobalRef(Main, :somethingelse)),
+        Core.Compiler.GotoIfNot(Core.SSAValue(6), 9),
+        # block 5
+        Core.Compiler.ReturnNode(Core.SSAValue(6)),
+        # block 6
+        Core.Compiler.ReturnNode(Core.SSAValue(6))
+    ]
+    nstmts = length(ci.code)
+    ci.ssavaluetypes = nstmts
+    ci.codelocs = fill(Int32(1), nstmts)
+    ci.ssaflags = fill(Int32(0), nstmts)
+    ir = Core.Compiler.inflate_ir(ci)
+    ir = Core.Compiler.compact!(ir, true)
+    @test Core.Compiler.verify_ir(ir) == nothing
+end