From a9f6bbea62f42ab052eca423588e309ab67c3fa3 Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Mon, 13 Dec 2010 08:12:19 +0000
Subject: [PATCH] reinstate my patch: the miscompile was caused by an inverted
 branch in the 'and' case.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121695 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Utils/SimplifyCFG.cpp         |  9 ++-
 test/Transforms/SimplifyCFG/switch_create.ll | 75 +++++++++++++-------
 2 files changed, 54 insertions(+), 30 deletions(-)

diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index d7a6ea4655a..71d9ef84832 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -1909,13 +1909,15 @@ static bool SimplifyBranchOnICmpChain(BranchInst *BI, const TargetData *TD) {
   // then we evaluate them with an explicit branch first.  Split the block
   // right before the condbr to handle it.
   if (ExtraCase) {
-    return false;
-    
     BasicBlock *NewBB = BB->splitBasicBlock(BI, "switch.early.test");
     // Remove the uncond branch added to the old block.
     TerminatorInst *OldTI = BB->getTerminator();
     
-    BranchInst::Create(EdgeBB, NewBB, ExtraCase, OldTI);
+    if (TrueWhenEqual)
+      BranchInst::Create(EdgeBB, NewBB, ExtraCase, OldTI);
+    else
+      BranchInst::Create(NewBB, EdgeBB, ExtraCase, OldTI);
+      
     OldTI->eraseFromParent();
     
     // If there are PHI nodes in EdgeBB, then we need to add a new entry to them
@@ -1955,6 +1957,7 @@ static bool SimplifyBranchOnICmpChain(BranchInst *BI, const TargetData *TD) {
   
   // Erase the old branch instruction.
   EraseTerminatorInstAndDCECond(BI);
+  
   return true;
 }
 
diff --git a/test/Transforms/SimplifyCFG/switch_create.ll b/test/Transforms/SimplifyCFG/switch_create.ll
index 2f0dc94c08f..5b96c6b16be 100644
--- a/test/Transforms/SimplifyCFG/switch_create.ll
+++ b/test/Transforms/SimplifyCFG/switch_create.ll
@@ -168,13 +168,13 @@ if.end:                                           ; preds = %entry
   ret void
   
 ; CHECK: @test7
-; HECK:   %cmp = icmp ult i32 %x, 32
-; HECK:   br i1 %cmp, label %if.then, label %switch.early.test
-; HECK: switch.early.test:
-; HECK:   switch i8 %c, label %if.end [
-; HECK:     i8 99, label %if.then
-; HECK:     i8 97, label %if.then
-; HECK:   ]
+; CHECK:   %cmp = icmp ult i32 %x, 32
+; CHECK:   br i1 %cmp, label %if.then, label %switch.early.test
+; CHECK: switch.early.test:
+; CHECK:   switch i8 %c, label %if.end [
+; CHECK:     i8 99, label %if.then
+; CHECK:     i8 97, label %if.then
+; CHECK:   ]
 }
 
 define i32 @test8(i8 zeroext %c, i32 %x, i1 %C) nounwind ssp noredzone {
@@ -197,12 +197,12 @@ if.end:                                           ; preds = %entry
   ret i32 0
   
 ; CHECK: @test8
-; HECK: switch.early.test:
-; HECK:   switch i8 %c, label %if.end [
-; HECK:     i8 99, label %if.then
-; HECK:     i8 97, label %if.then
-; HECK:   ]
-; HECK:   %A = phi i32 [ 0, %entry ], [ 42, %switch.early.test ], [ 42, %N ], [ 42, %switch.early.test ]
+; CHECK: switch.early.test:
+; CHECK:   switch i8 %c, label %if.end [
+; CHECK:     i8 99, label %if.then
+; CHECK:     i8 97, label %if.then
+; CHECK:   ]
+; CHECK:   %A = phi i32 [ 0, %entry ], [ 42, %switch.early.test ], [ 42, %N ], [ 42, %switch.early.test ]
 }
 
 ;; This is "Example 7" from http://blog.regehr.org/archives/320
@@ -254,20 +254,41 @@ lor.end:                                          ; preds = %lor.rhs, %lor.lhs.f
   
 ; CHECK: @test9
 ; CHECK:   %cmp = icmp ult i8 %c, 33
-; HECK:   br i1 %cmp, label %lor.end, label %switch.early.test
-
-; HECK: switch.early.test:
-; HECK:   switch i8 %c, label %lor.rhs [
-; HECK:     i8 46, label %lor.end
-; HECK:     i8 44, label %lor.end
-; HECK:     i8 58, label %lor.end
-; HECK:     i8 59, label %lor.end
-; HECK:     i8 60, label %lor.end
-; HECK:     i8 62, label %lor.end
-; HECK:     i8 34, label %lor.end
-; HECK:     i8 92, label %lor.end
-; HECK:     i8 39, label %lor.end
-; HECK:   ]
+; CHECK:   br i1 %cmp, label %lor.end, label %switch.early.test
+
+; CHECK: switch.early.test:
+; CHECK:   switch i8 %c, label %lor.rhs [
+; CHECK:     i8 46, label %lor.end
+; CHECK:     i8 44, label %lor.end
+; CHECK:     i8 58, label %lor.end
+; CHECK:     i8 59, label %lor.end
+; CHECK:     i8 60, label %lor.end
+; CHECK:     i8 62, label %lor.end
+; CHECK:     i8 34, label %lor.end
+; CHECK:     i8 92, label %lor.end
+; CHECK:     i8 39, label %lor.end
+; CHECK:   ]
 }
 
+define i32 @test10(i32 %mode, i1 %Cond) {
+  %A = icmp ne i32 %mode, 0
+  %B = icmp ne i32 %mode, 51
+  %C = and i1 %A, %B
+  %D = and i1 %C, %Cond
+  br i1 %D, label %T, label %F
+T:
+  ret i32 123
+F:
+  ret i32 324
+
+; CHECK: @test10
+; CHECK:  br i1 %Cond, label %switch.early.test, label %F
+; CHECK:switch.early.test:
+; CHECK:  switch i32 %mode, label %T [
+; CHECK:    i32 51, label %F
+; CHECK:    i32 0, label %F
+; CHECK:  ]
+}
+
+
 
-- 
2.34.1