Factor out Instruction::isSafeToSpeculativelyExecute's code for

testing for dereferenceable pointers into a helper function,
isDereferenceablePointer.  Teach it how to reason about GEPs
with simple non-zero indices.

Also eliminate ArgumentPromtion's IsAlwaysValidPointer,
which didn't check for weak externals or out of range gep
indices.

llvm-svn: 118840

1 files changed, 94 insertions, 0 deletions

diff --git a/llvm/test/Transforms/SimplifyCFG/speculate-with-offset.ll b/llvm/test/Transforms/SimplifyCFG/speculate-with-offset.ll
new file mode 100644
index 00000000000..a737d5602e8
--- /dev/null
+++ b/llvm/test/Transforms/SimplifyCFG/speculate-with-offset.ll
@@ -0,0 +1,94 @@
+; RUN: opt -simplifycfg -S < %s | FileCheck %s
+
+; This load is safe to speculate, as it's from a safe offset
+; within an alloca.
+
+; CHECK: @yes
+; CHECK-NOT: br
+
+define void @yes(i1 %c) nounwind {
+entry:
+  %a = alloca [4 x i64*], align 8
+  %__a.addr = getelementptr [4 x i64*]* %a, i64 0, i64 3
+  call void @frob(i64** %__a.addr)
+  br i1 %c, label %if.then, label %if.end
+
+if.then:                                          ; preds = %entry
+  br label %return
+
+if.end:                                           ; preds = %entry
+  %tmp5 = load i64** %__a.addr, align 8
+  br label %return
+
+return:                                           ; preds = %if.end, %if.then
+  %storemerge = phi i64* [ undef, %if.then ], [ %tmp5, %if.end ]
+  ret void
+}
+
+; CHECK: @no0
+; CHECK: br i1 %c
+
+define void @no0(i1 %c) nounwind {
+entry:
+  %a = alloca [4 x i64*], align 8
+  %__a.addr = getelementptr [4 x i64*]* %a, i64 0, i64 4
+  call void @frob(i64** %__a.addr)
+  br i1 %c, label %if.then, label %if.end
+
+if.then:                                          ; preds = %entry
+  br label %return
+
+if.end:                                           ; preds = %entry
+  %tmp5 = load i64** %__a.addr, align 8
+  br label %return
+
+return:                                           ; preds = %if.end, %if.then
+  %storemerge = phi i64* [ undef, %if.then ], [ %tmp5, %if.end ]
+  ret void
+}
+
+; CHECK: @no1
+; CHECK: br i1 %c
+
+define void @no1(i1 %c, i64 %n) nounwind {
+entry:
+  %a = alloca [4 x i64*], align 8
+  %__a.addr = getelementptr [4 x i64*]* %a, i64 0, i64 %n
+  call void @frob(i64** %__a.addr)
+  br i1 %c, label %if.then, label %if.end
+
+if.then:                                          ; preds = %entry
+  br label %return
+
+if.end:                                           ; preds = %entry
+  %tmp5 = load i64** %__a.addr, align 8
+  br label %return
+
+return:                                           ; preds = %if.end, %if.then
+  %storemerge = phi i64* [ undef, %if.then ], [ %tmp5, %if.end ]
+  ret void
+}
+
+; CHECK: @no2
+; CHECK: br i1 %c
+
+define void @no2(i1 %c, i64 %n) nounwind {
+entry:
+  %a = alloca [4 x i64*], align 8
+  %__a.addr = getelementptr [4 x i64*]* %a, i64 1, i64 0
+  call void @frob(i64** %__a.addr)
+  br i1 %c, label %if.then, label %if.end
+
+if.then:                                          ; preds = %entry
+  br label %return
+
+if.end:                                           ; preds = %entry
+  %tmp5 = load i64** %__a.addr, align 8
+  br label %return
+
+return:                                           ; preds = %if.end, %if.then
+  %storemerge = phi i64* [ undef, %if.then ], [ %tmp5, %if.end ]
+  ret void
+}
+
+declare void @frob(i64** nocapture %p)