Fix indvars to not assume that a loop with a single unique exit

block has a single unique exiting block.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75579 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/IndVarSimplify.cpp b/lib/Transforms/Scalar/IndVarSimplify.cpp
index 365589dc0dab99b68309976ad0cf7531f8478269..911545d86f3e6d48eaee6026f916edea3d99114d 100644 (file)
--- a/lib/Transforms/Scalar/IndVarSimplify.cpp
+++ b/lib/Transforms/Scalar/IndVarSimplify.cpp
@@ -281,17 +281,15 @@ void IndVarSimplify::RewriteLoopExitValues(Loop *L,
         // If this instruction is dead now, delete it.
         RecursivelyDeleteTriviallyDeadInstructions(Inst);
 
-        // If we're inserting code into the exit block rather than the
-        // preheader, we can (and have to) remove the PHI entirely.
-        // This is safe, because the NewVal won't be variant
-        // in the loop, so we don't need an LCSSA phi node anymore.
-        if (ExitBlocks.size() == 1) {
+        if (NumPreds == 1) {
+          // Completely replace a single-pred PHI. This is safe, because the
+          // NewVal won't be variant in the loop, so we don't need an LCSSA phi
+          // node anymore.
           PN->replaceAllUsesWith(ExitVal);
           RecursivelyDeleteTriviallyDeadInstructions(PN);
-          break;
         }
       }
-      if (ExitBlocks.size() != 1) {
+      if (NumPreds != 1) {
         // Clone the PHI and delete the original one. This lets IVUsers and
         // any other maps purge the original user from their records.
         PHINode *NewPN = PN->clone(*Context);

diff --git a/test/Transforms/IndVarSimplify/loop_evaluate10.ll b/test/Transforms/IndVarSimplify/loop_evaluate10.ll
new file mode 100644 (file)
index 0000000..3766333
--- /dev/null
+++ b/test/Transforms/IndVarSimplify/loop_evaluate10.ll
@@ -0,0 +1,47 @@
+; RUN: llvm-as < %s | opt -indvars | llvm-dis \
+; RUN:   | grep {%b.1 = phi i32 \\\[ 2, %bb \\\], \\\[ 1, %bb2 \\\]}
+
+; This loop has multiple exits, and the value of %b1 depends on which
+; exit is taken. Indvars should correctly compute the exit values.
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
+target triple = "x86_64-linux-gnu"
+       %struct..0anon = type <{ i8, [3 x i8] }>
+
+define i32 @main() nounwind {
+entry:
+       br label %bb2
+
+bb2:           ; preds = %bb, %entry
+       %sdata.0 = phi i32 [ 1, %entry ], [ %ins10, %bb ]               ; <i32> [#uses=2]
+       %b.0 = phi i32 [ 0, %entry ], [ %t0, %bb ]              ; <i32> [#uses=2]
+       %tmp6 = trunc i32 %sdata.0 to i8                ; <i8> [#uses=2]
+       %t2 = and i8 %tmp6, 1           ; <i8> [#uses=1]
+       %t3 = icmp eq i8 %t2, 0         ; <i1> [#uses=1]
+       %t4 = xor i8 %tmp6, 1           ; <i8> [#uses=1]
+       %tmp8 = zext i8 %t4 to i32              ; <i32> [#uses=1]
+       %mask9 = and i32 %sdata.0, -256         ; <i32> [#uses=1]
+       %ins10 = or i32 %tmp8, %mask9           ; <i32> [#uses=1]
+       br i1 %t3, label %bb3, label %bb
+
+bb:            ; preds = %bb2
+       %t0 = add i32 %b.0, 1           ; <i32> [#uses=3]
+       %t1 = icmp sgt i32 %t0, 100             ; <i1> [#uses=1]
+       br i1 %t1, label %bb3, label %bb2
+
+bb3:           ; preds = %bb, %bb2
+       %b.1 = phi i32 [ %t0, %bb ], [ %b.0, %bb2 ]             ; <i32> [#uses=1]
+       %t5 = icmp eq i32 %b.1, 1               ; <i1> [#uses=1]
+       br i1 %t5, label %bb5, label %bb4
+
+bb4:           ; preds = %bb3
+       tail call void @abort() noreturn nounwind
+       unreachable
+
+bb5:           ; preds = %bb3
+       ret i32 0
+}
+
+declare void @llvm.memset.i64(i8* nocapture, i8, i64, i32) nounwind
+
+declare void @abort() noreturn nounwind