LSR: handle the expansion of phi operands that use postinc forms of the IV.

Fixes PR11431: SCEVExpander::expandAddRecExprLiterally(const llvm::SCEVAddRecExpr*): Assertion `(!isa<Instruction>(Result) || SE.DT->dominates(cast<Instruction>(Result), Builder.GetInsertPoint())) && "postinc expansion does not dominate use"' failed.

llvm-svn: 145482

1 files changed, 56 insertions, 0 deletions

diff --git a/llvm/test/Transforms/LoopStrengthReduce/2011-11-29-postincphi.ll b/llvm/test/Transforms/LoopStrengthReduce/2011-11-29-postincphi.ll
new file mode 100644
index 00000000000..3f9953e4724
--- /dev/null
+++ b/llvm/test/Transforms/LoopStrengthReduce/2011-11-29-postincphi.ll
@@ -0,0 +1,56 @@
+; RUN: llc < %s | FileCheck %s
+;
+; PR11431: handle a phi operand that is replaced by a postinc user.
+; LSR first expands %mul to %iv1 in %phi32
+; LSR then expands %iv1 in %phi32 into two decrements, one on each loop exit.
+
+target datalayout = "e-p:64:64:64-S128-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-f128:128:128-n8:16:32:64"
+target triple = "x86_64-unknown-linux-gnu"
+
+declare i1 @check() nounwind
+
+; Check that LSR did something close to the behavior at the time of the bug.
+; CHECK: @sqlite3DropTriggerPtr
+; CHECK: addq $48, %rax
+; CHECK: je
+; CHECK: addq $-48, %rax
+; CHECK: ret
+define i64 @sqlite3DropTriggerPtr() {
+entry:
+  %cmp0 = call zeroext i1 @check()
+  br i1 %cmp0, label %"8", label %"3"
+
+"3":                                              ; preds = %entry
+  br i1 %cmp0, label %"4", label %"8"
+
+"4":                                              ; preds = %"3"
+  br i1 %cmp0, label %"8", label %"5.preheader"
+
+"5.preheader":                                    ; preds = %"4"
+  br label %"5"
+
+"5":
+  %iv0 = phi i32 [ %iv0.inc, %"6" ], [ 0, %"5.preheader" ]
+  %iv1 = phi i64 [ %iv1.inc, %"6" ], [ 48, %"5.preheader" ]
+  %iv0.inc = add nsw i32 %iv0, 1
+  %cmp = icmp eq i32 %iv0.inc, 0
+  br i1 %cmp, label %"7", label %"6"
+
+"6":
+  %iv1.inc = add i64 %iv1, 48
+  %iv1.ofs = add i64 %iv1, 40
+  %ptr8 = getelementptr inbounds i8* undef, i64 %iv1.ofs
+  %ptr32 = bitcast i8* %ptr8 to i32**
+  %v = load i32** %ptr32, align 8
+  br i1 %cmp0, label %"8", label %"5"
+
+"7":
+  %iv.inc64 = sext i32 %iv0.inc to i64
+  %mul = mul i64 %iv.inc64, 48
+  br label %"8"
+
+"8":                                              ; preds = %"7", %"5", %"4", %"3", %entry
+  %phi32 = phi i32 [ %iv0.inc, %"7" ], [ 0, %"4" ], [ 0, %"3" ], [ -1000000, %entry ], [ %iv0.inc, %"6" ]
+  %phi64 = phi i64 [ %mul, %"7" ], [ 0, %"4" ], [ 0, %"3" ], [ -48000000, %entry ], [ %iv1, %"6" ]
+  ret i64 %phi64
+}