[MemorySSAUpdater] Update Phi operands after trivial Phi elimination

Bug fix for PR37445. The underlying problem and its fix are similar to PR37808.
The bug lies in MemorySSAUpdater::getPreviousDefRecursive(), where PhiOps is
computed before the call to tryRemoveTrivialPhi() and it ends up being out of
date, pointing to stale data. We have now turned each of the PhiOps into a
TrackingVH<MemoryAccess>.

Differential Revision: https://reviews.llvm.org/D49425

llvm-svn: 337680

1 files changed, 119 insertions, 0 deletions

diff --git a/llvm/test/Transforms/GVNHoist/pr37445.ll b/llvm/test/Transforms/GVNHoist/pr37445.ll
new file mode 100644
index 00000000000..817fea14077
--- /dev/null
+++ b/llvm/test/Transforms/GVNHoist/pr37445.ll
@@ -0,0 +1,119 @@
+; RUN: opt < %s -early-cse-memssa -gvn-hoist -S | FileCheck %s
+
+; Make sure opt won't crash and that this pair of
+; instructions (load, icmp) is hoisted successfully
+; from bb45 and bb58 to bb41.
+
+@g_10 = external global i32, align 4
+@g_536 = external global i8*, align 8
+@g_1629 = external global i32**, align 8
+@g_963 = external global i32**, align 8
+@g_1276 = external global i32**, align 8
+
+;CHECK-LABEL: @func_22
+
+define void @func_22(i32* %arg, i32* %arg1) {
+bb:
+  br label %bb12
+
+bb12:
+  %tmp3.0 = phi i32 [ undef, %bb ], [ %tmp40, %bb36 ]
+  %tmp7.0 = phi i32 [ undef, %bb ], [ %spec.select, %bb36 ]
+  %tmp14 = icmp eq i32 %tmp3.0, 6
+  br i1 %tmp14, label %bb41, label %bb15
+
+bb15:
+  %tmp183 = trunc i16 0 to i8
+  %tmp20 = load i8*, i8** @g_536, align 8
+  %tmp21 = load i8, i8* %tmp20, align 1
+  %tmp23 = or i8 %tmp21, %tmp183
+  store i8 %tmp23, i8* %tmp20, align 1
+  %tmp5.i = icmp eq i8 %tmp23, 0
+  br i1 %tmp5.i, label %safe_div_func_uint8_t_u_u.exit, label %bb8.i
+
+bb8.i:
+  %0 = udiv i8 1, %tmp23
+  br label %safe_div_func_uint8_t_u_u.exit
+
+safe_div_func_uint8_t_u_u.exit:
+  %tmp13.in.i = phi i8 [ %0, %bb8.i ], [ 1, %bb15 ]
+  %tmp31 = icmp eq i8 %tmp13.in.i, 0
+  %spec.select = select i1 %tmp31, i32 %tmp7.0, i32 53
+  %tmp35 = icmp eq i32 %spec.select, 0
+  br i1 %tmp35, label %bb36, label %bb41
+
+bb36:
+  %tmp38 = sext i32 %tmp3.0 to i64
+  %tmp40 = trunc i64 %tmp38 to i32
+  br label %bb12
+
+;CHECK: bb41:
+;CHECK:   %tmp47 = load i32, i32* %arg1, align 4
+;CHECK:   %tmp48 = icmp eq i32 %tmp47, 0
+
+bb41:
+  %tmp43 = load i32, i32* %arg, align 4
+  %tmp44 = icmp eq i32 %tmp43, 0
+  br i1 %tmp44, label %bb52, label %bb45
+
+;CHECK:     bb45:
+;CHECK-NOT:   %tmp47 = load i32, i32* %arg1, align 4
+;CHECK-NOT:   %tmp48 = icmp eq i32 %tmp47, 0
+
+bb45:
+  %tmp47 = load i32, i32* %arg1, align 4
+  %tmp48 = icmp eq i32 %tmp47, 0
+  br i1 %tmp48, label %bb50, label %bb64
+
+bb50:
+  %tmp51 = load volatile i32**, i32*** @g_963, align 8
+  unreachable
+
+bb52:
+  %tmp8.0 = phi i32 [ undef, %bb41 ], [ %tmp57, %bb55 ]
+  %tmp54 = icmp slt i32 %tmp8.0, 3
+  br i1 %tmp54, label %bb55, label %bb58
+
+bb55:
+  %tmp57 = add nsw i32 %tmp8.0, 1
+  br label %bb52
+
+;CHECK:     bb58:
+;CHECK-NOT:   %tmp60 = load i32, i32* %arg1, align 4
+;CHECK-NOT:   %tmp61 = icmp eq i32 %tmp60, 0
+
+bb58:
+  %tmp60 = load i32, i32* %arg1, align 4
+  %tmp61 = icmp eq i32 %tmp60, 0
+  br i1 %tmp61, label %bb62, label %bb64
+
+bb62:
+  %tmp63 = load volatile i32**, i32*** @g_1276, align 8
+  unreachable
+
+bb64:
+  %tmp65 = load volatile i32**, i32*** @g_1629, align 8
+  unreachable
+
+; uselistorder directives
+  uselistorder i32 %spec.select, { 1, 0 }
+  uselistorder i32* %arg1, { 1, 0 }
+  uselistorder label %bb64, { 1, 0 }
+  uselistorder label %bb52, { 1, 0 }
+  uselistorder label %bb41, { 1, 0 }
+  uselistorder label %safe_div_func_uint8_t_u_u.exit, { 1, 0 }
+}
+
+define zeroext i8 @safe_div_func_uint8_t_u_u(i8 zeroext %arg, i8 zeroext %arg1) {
+bb:
+  %tmp5 = icmp eq i8 %arg1, 0
+  br i1 %tmp5, label %bb12, label %bb8
+
+bb8:
+  %0 = udiv i8 %arg, %arg1
+  br label %bb12
+
+bb12:
+  %tmp13.in = phi i8 [ %0, %bb8 ], [ %arg, %bb ]
+  ret i8 %tmp13.in
+}