[SimplifyLibCalls] Fix negative shifts being produced by the memchr -> bitfield trans...

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232903 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Utils/SimplifyLibCalls.cpp b/lib/Transforms/Utils/SimplifyLibCalls.cpp
index f6cc431656b806fbfe18359fd63b4c1ce88f1174..5867d65e7e415944194a46a1ef358024e3bdc218 100644 (file)
--- a/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -782,7 +782,9 @@ Value *LibCallSimplifier::optimizeMemChr(CallInst *CI, IRBuilder<> &B) {
   // memchr("\r\n", C, 2) != nullptr -> (C & ((1 << '\r') | (1 << '\n'))) != 0
   //   after bounds check.
   if (!CharC && !Str.empty() && isOnlyUsedInZeroEqualityComparison(CI)) {
-    unsigned char Max = *std::max_element(Str.begin(), Str.end());
+    unsigned char Max =
+        *std::max_element(reinterpret_cast<const unsigned char *>(Str.begin()),
+                          reinterpret_cast<const unsigned char *>(Str.end()));
 
     // Make sure the bit field we're about to create fits in a register on the
     // target.

diff --git a/test/Transforms/InstCombine/memchr.ll b/test/Transforms/InstCombine/memchr.ll
index 6783249877d3f3cf44baf2e8d7a1dc8e7dcbbaf0..216dba874ccb20939d5d6b07c3ba94a242e46f68 100644 (file)
--- a/test/Transforms/InstCombine/memchr.ll
+++ b/test/Transforms/InstCombine/memchr.ll
@@ -9,6 +9,7 @@ target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f3
 @newlines = constant [3 x i8] c"\0D\0A\00"
 @single = constant [2 x i8] c"\1F\00"
 @spaces = constant [4 x i8] c" \0D\0A\00"
+@negative = constant [3 x i8] c"\FF\FE\00"
 @chp = global i8* zeroinitializer
 
 declare i8* @memchr(i8*, i32, i32)
@@ -186,3 +187,14 @@ define i1 @test14(i32 %C) {
   %cmp = icmp ne i8* %dst, null
   ret i1 %cmp
 }
+
+define i1 @test15(i32 %C) {
+; CHECK-LABEL: @test15
+; CHECK-NEXT: %dst = call i8* @memchr(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @negative, i32 0, i32 0), i32 %C, i32 3)
+; CHECK-NEXT: %cmp = icmp ne i8* %dst, null
+; CHECK-NEXT: ret i1 %cmp
+
+  %dst = call i8* @memchr(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @negative, i64 0, i64 0), i32 %C, i32 3)
+  %cmp = icmp ne i8* %dst, null
+  ret i1 %cmp
+}