[MC] Fix constant pools with DenseMap sentinel values

The MC ConstantPool class uses a DenseMap to track generated constants, with
the int64_t value of the constant as the key. This fails when values of
0x7fffffffffffffff or 0x7ffffffffffffffe are inserted into the constant pool, as
these are sentinel values for DenseMap.

The fix is to use std::map instead, which doesn't use sentinel values.

Differential revision: https://reviews.llvm.org/D33667

llvm-svn: 304199

2 files changed, 14 insertions, 1 deletions

diff --git a/llvm/include/llvm/MC/ConstantPools.h b/llvm/include/llvm/MC/ConstantPools.h
index 5d4e32a672d..ef33250204e 100644
--- a/llvm/include/llvm/MC/ConstantPools.h
+++ b/llvm/include/llvm/MC/ConstantPools.h
@@ -19,6 +19,7 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/SMLoc.h"
 #include <cstdint>
+#include <map>
 
 namespace llvm {
 
@@ -44,7 +45,7 @@ struct ConstantPoolEntry {
 class ConstantPool {
   using EntryVecTy = SmallVector<ConstantPoolEntry, 4>;
   EntryVecTy Entries;
-  DenseMap<int64_t, const MCSymbolRefExpr *> CachedEntries;
+  std::map<int64_t, const MCSymbolRefExpr *> CachedEntries;
 
 public:
   // Initialize a new empty constant pool
diff --git a/llvm/test/MC/AArch64/ldr-pseudo.s b/llvm/test/MC/AArch64/ldr-pseudo.s
index e132f7cf651..1d99d140180 100644
--- a/llvm/test/MC/AArch64/ldr-pseudo.s
+++ b/llvm/test/MC/AArch64/ldr-pseudo.s
@@ -205,6 +205,13 @@ f18:
   ldr x1, =0x320064
 // CHECK: ldr x1, .Ltmp[[TMP26:[0-9]+]]
 
+// We previously used a DenseMap with constant values as keys, check that
+// sentinel values can be used.
+  ldr x0, =0x7ffffffffffffffe
+// CHECK: ldr x0, .Ltmp[[TMP27:[0-9]+]]
+  ldr x1, =0x7fffffffffffffff
+// CHECK: ldr x1, .Ltmp[[TMP28:[0-9]+]]
+
 //
 // Constant Pools
 //
@@ -311,3 +318,8 @@ f18:
 // CHECK: .p2align 2
 // CHECK: .Ltmp[[TMP25]]
 // CHECK: .word 3276900
+
+// CHECK: .Ltmp[[TMP27]]
+// CHECK: .xword 9223372036854775806
+// CHECK: .Ltmp[[TMP28]]
+// CHECK: .xword 9223372036854775807