From b71bb80c2debeab7128ce9be440d6601260910cd Mon Sep 17 00:00:00 2001
From: Serge Pavlov <sepavloff@gmail.com>
Date: Sun, 26 Mar 2017 16:46:53 +0000
Subject: [PATCH] [LoopUnroll] Remap references in peeled iteration

References in cloned blocks must be remapped prior to dominator
calculation.

Differential Revision: https://reviews.llvm.org/D31281

llvm-svn: 298811
---
 llvm/lib/Transforms/Utils/LoopUnrollPeel.cpp  |  9 ++--
 llvm/test/Transforms/LoopUnroll/peel-loop2.ll | 61 +++++++++++++++++++++++++++
 2 files changed, 66 insertions(+), 4 deletions(-)
 create mode 100644 llvm/test/Transforms/LoopUnroll/peel-loop2.ll

diff --git a/llvm/lib/Transforms/Utils/LoopUnrollPeel.cpp b/llvm/lib/Transforms/Utils/LoopUnrollPeel.cpp
index ea3e37d..73c14f5 100644
--- a/llvm/lib/Transforms/Utils/LoopUnrollPeel.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUnrollPeel.cpp
@@ -415,6 +415,11 @@ bool llvm::peelLoop(Loop *L, unsigned PeelCount, LoopInfo *LI,
 
     cloneLoopBlocks(L, Iter, InsertTop, InsertBot, Exit,
                     NewBlocks, LoopBlocks, VMap, LVMap, DT, LI);
+
+    // Remap to use values from the current iteration instead of the
+    // previous one.
+    remapInstructionsInBlocks(NewBlocks, VMap);
+
     if (DT) {
       // Latches of the cloned loops dominate over the loop exit, so idom of the
       // latter is the first cloned loop body, as original PreHeader dominates
@@ -437,10 +442,6 @@ bool llvm::peelLoop(Loop *L, unsigned PeelCount, LoopInfo *LI,
     F->getBasicBlockList().splice(InsertTop->getIterator(),
                                   F->getBasicBlockList(),
                                   NewBlocks[0]->getIterator(), F->end());
-
-    // Remap to use values from the current iteration instead of the
-    // previous one.
-    remapInstructionsInBlocks(NewBlocks, VMap);
   }
 
   // Now adjust the phi nodes in the loop header to get their initial values
diff --git a/llvm/test/Transforms/LoopUnroll/peel-loop2.ll b/llvm/test/Transforms/LoopUnroll/peel-loop2.ll
new file mode 100644
index 0000000..99e9079
--- /dev/null
+++ b/llvm/test/Transforms/LoopUnroll/peel-loop2.ll
@@ -0,0 +1,61 @@
+; RUN: opt -S -loop-unroll -unroll-force-peel-count=1 -verify-dom-info <%s
+
+; Check if loop composed of several BBs is peeled correctly.
+
+declare void @funcb()
+@Comma = external global i8
+define void @funca(i8* readnone %b, i8* readnone %e) {
+entry:
+  %cmp2 = icmp eq i8* %b, %e
+  br i1 %cmp2, label %for.end, label %for.body.preheader
+
+for.body.preheader:
+  br label %for.body
+
+for.body:
+  %b.addr.03 = phi i8* [ %incdec.ptr, %for.inc ], [ %b, %for.body.preheader ]
+  %0 = load i8, i8* @Comma
+  %tobool = icmp eq i8 %0, 0
+  br i1 %tobool, label %for.inc, label %if.then
+
+if.then:
+  tail call void @funcb()
+  store i8 1, i8* @Comma
+  br label %for.inc
+
+for.inc:
+  %incdec.ptr = getelementptr inbounds i8, i8* %b.addr.03, i64 1
+  %cmp = icmp eq i8* %incdec.ptr, %e
+  br i1 %cmp, label %for.end, label %for.body
+
+for.end:
+  ret void
+}
+
+; CHECK_LABEL: @funca
+
+; Peeled iteration
+; CHECK: %[[REG1:[0-9]+]] = load i8, i8* @Comma
+; CHECK: %[[REG2:.*]] = icmp eq i8 %[[REG1]], 0
+; CHECK: br i1 %[[REG2]], label %{{.*}}, label %[[IFTHEN:.*]]
+; CHECK: [[IFTHEN]]:
+; CHECK: call void @funcb()
+; CHECK: store i8 1, i8* @Comma
+; CHECK: br label %[[FORINC]]
+; CHECK: [[FORINC]]:
+; CHECK: %[[REG3:.*]] = getelementptr inbounds i8, i8* %b, i64 1
+; CHECK: %[[REG4:.*]] = icmp eq i8* %[[REG3]], %e
+; CHECK: br i1 %[[REG4]]
+
+; main body
+; CHECK: %[[REG1b:.*]] = load i8, i8* @Comma
+; CHECK: %[[REG2b:.*]] = icmp eq i8 %[[REG1b]], 0
+; CHECK: br i1 %[[REG2b]], label %{{.*}}, label %[[IFTHENb:.*]]
+; CHECK: [[IFTHENb]]:
+; CHECK: call void @funcb()
+; CHECK: store i8 1, i8* @Comma
+; CHECK: br label %[[FORINCb]]
+; CHECK: [[FORINCb]]:
+; CHECK: %[[REG3b:.*]] = getelementptr inbounds i8, i8* %b, i64 1
+; CHECK: %[[REG4b:.*]] = icmp eq i8* %[[REG3b]], %e
+; CHECK: br i1 %[[REG4b]]
-- 
2.7.4