Added special handling for inttoptr in CFLAA.

We now treat pointers given to ptrtoint and pointers retrieved from
inttoptr as similar to arguments or globals (can alias anything, etc.)

This solves some of the problems we were having with giving incorrect
results.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231741 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 73 insertions, 0 deletions

diff --git a/test/Analysis/CFLAliasAnalysis/branch-alias.ll b/test/Analysis/CFLAliasAnalysis/branch-alias.ll
new file mode 100644
index 00000000000..8307462928e
--- /dev/null
+++ b/test/Analysis/CFLAliasAnalysis/branch-alias.ll
@@ -0,0 +1,73 @@
+; Makes sure that we give up on some pathological cases with inttoptr/ptrtoint
+;
+; @ptr_test was generated from the following C code:
+;  void ptr_test() {
+;    int* A;
+;    unsigned long RefCopy = 0;
+;    for (int i = 0; i < 8*sizeof(&A); ++i) {
+;      if ((unsigned long)&A & (1UL << i))
+;        RefCopy |= 1UL << i;
+;    }
+;
+;    int** AliasA1 = (int**)RefCopy;
+;    int* ShouldAliasA = *AliasA1;
+;  }
+
+; RUN: opt < %s -cfl-aa -aa-eval -print-may-aliases -disable-output 2>&1 | FileCheck %s
+
+; CHECK: Function: ptr_test
+define void @ptr_test() #0 {
+  ; CHECK: MayAlias: i32** %A, i32** %ShouldAliasA
+  ; CHECK-NOT: %AliasA1
+entry:
+  %A = alloca i32*, align 8
+  %RefCopy = alloca i64, align 8
+  %i = alloca i32, align 4
+  %AliasA1 = alloca i32**, align 8
+  %ShouldAliasA = alloca i32*, align 8
+  store i64 0, i64* %RefCopy, align 8
+  store i32 0, i32* %i, align 4
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.inc, %entry
+  %0 = load i32, i32* %i, align 4
+  %conv = sext i32 %0 to i64
+  %cmp = icmp ult i64 %conv, 64
+  br i1 %cmp, label %for.body, label %for.end
+
+for.body:                                         ; preds = %for.cond
+  %1 = ptrtoint i32** %A to i64
+  %2 = load i32, i32* %i, align 4
+  %sh_prom = zext i32 %2 to i64
+  %shl = shl i64 1, %sh_prom
+  %and = and i64 %1, %shl
+  %tobool = icmp ne i64 %and, 0
+  br i1 %tobool, label %if.then, label %if.end
+
+if.then:                                          ; preds = %for.body
+  %3 = load i32, i32* %i, align 4
+  %sh_prom2 = zext i32 %3 to i64
+  %shl3 = shl i64 1, %sh_prom2
+  %4 = load i64, i64* %RefCopy, align 8
+  %or = or i64 %4, %shl3
+  store i64 %or, i64* %RefCopy, align 8
+  br label %if.end
+
+if.end:                                           ; preds = %if.then, %for.body
+  br label %for.inc
+
+for.inc:                                          ; preds = %if.end
+  %5 = load i32, i32* %i, align 4
+  %inc = add nsw i32 %5, 1
+  store i32 %inc, i32* %i, align 4
+  br label %for.cond
+
+for.end:                                          ; preds = %for.cond
+  %6 = load i64, i64* %RefCopy, align 8
+  %7 = inttoptr i64 %6 to i32**
+  store i32** %7, i32*** %AliasA1, align 8
+  %8 = load i32**, i32*** %AliasA1, align 8
+  %9 = load i32*, i32** %8, align 8
+  store i32* %9, i32** %ShouldAliasA, align 8
+  ret void
+}