[llvm-commits] [llvm] r75579 - in /llvm/trunk: lib/Transforms/Scalar/IndVarSimplify.cpp test/Transforms/IndVarSimplify/loop_evaluate10.ll

[Dan Gohman]

Author: djg
Date: Mon Jul 13 20:09:02 2009
New Revision: 75579

URL: http://llvm.org/viewvc/llvm-project?rev=75579&view=rev
Log:
Fix indvars to not assume that a loop with a single unique exit
block has a single unique exiting block.

Added:
    llvm/trunk/test/Transforms/IndVarSimplify/loop_evaluate10.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/IndVarSimplify.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/IndVarSimplify.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/IndVarSimplify.cpp?rev=75579&r1=75578&r2=75579&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/IndVarSimplify.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/IndVarSimplify.cpp Mon Jul 13 20:09:02 2009
@@ -281,17 +281,15 @@
         // 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);

Added: llvm/trunk/test/Transforms/IndVarSimplify/loop_evaluate10.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/IndVarSimplify/loop_evaluate10.ll?rev=75579&view=auto

==============================================================================
--- llvm/trunk/test/Transforms/IndVarSimplify/loop_evaluate10.ll (added)
+++ llvm/trunk/test/Transforms/IndVarSimplify/loop_evaluate10.ll Mon Jul 13 20:09:02 2009
@@ -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