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

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block has a single unique exiting block.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75579 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2009-07-14 01:09:02 +00:00
parent a342026504
commit 65d1e2b6e7
2 changed files with 52 additions and 7 deletions
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12
lib/Transforms/Scalar/IndVarSimplify.cpp
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@ -281,17 +281,15 @@ void IndVarSimplify::RewriteLoopExitValues(Loop *L,
// If this instruction is dead now, delete it. // If this instruction is dead now, delete it.
RecursivelyDeleteTriviallyDeadInstructions(Inst); RecursivelyDeleteTriviallyDeadInstructions(Inst);
// If we're inserting code into the exit block rather than the if (NumPreds == 1) {
// preheader, we can (and have to) remove the PHI entirely. // Completely replace a single-pred PHI. This is safe, because the
// This is safe, because the NewVal won't be variant // NewVal won't be variant in the loop, so we don't need an LCSSA phi
// in the loop, so we don't need an LCSSA phi node anymore. // node anymore.
if (ExitBlocks.size() == 1) {
PN->replaceAllUsesWith(ExitVal); PN->replaceAllUsesWith(ExitVal);
RecursivelyDeleteTriviallyDeadInstructions(PN); RecursivelyDeleteTriviallyDeadInstructions(PN);
break;
} }
} }
if (ExitBlocks.size() != 1) { if (NumPreds != 1) {
// Clone the PHI and delete the original one. This lets IVUsers and // Clone the PHI and delete the original one. This lets IVUsers and
// any other maps purge the original user from their records. // any other maps purge the original user from their records.
PHINode *NewPN = PN->clone(*Context); PHINode *NewPN = PN->clone(*Context);

47
test/Transforms/IndVarSimplify/loop_evaluate10.ll Normal file
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@ -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