[X86] In OptimizeLEAs pass, check that the key is in the LEAs map before accessing
When the key is not already in the map, the access operator[] creates an empty value and grows the map.
Resizing a map is very slow, so this needs to be avoided.
Found with csmith + asserts.
May help with
https://bugs.llvm.org/show_bug.cgi?id=25843
Patch by Tom Rix.
Differential Revision: https://reviews.llvm.org/D50780
llvm-svn: 340434
diff --git a/llvm/lib/Target/X86/X86OptimizeLEAs.cpp b/llvm/lib/Target/X86/X86OptimizeLEAs.cpp
index 42db51b..b56d02b 100644
--- a/llvm/lib/Target/X86/X86OptimizeLEAs.cpp
+++ b/llvm/lib/Target/X86/X86OptimizeLEAs.cpp
@@ -510,12 +510,16 @@
MemOpNo += X86II::getOperandBias(Desc);
+ // Do not call chooseBestLEA if there was no matching LEA
+ auto Insns = LEAs.find(getMemOpKey(MI, MemOpNo));
+ if (Insns == LEAs.end())
+ continue;
+
// Get the best LEA instruction to replace address calculation.
MachineInstr *DefMI;
int64_t AddrDispShift;
int Dist;
- if (!chooseBestLEA(LEAs[getMemOpKey(MI, MemOpNo)], MI, DefMI, AddrDispShift,
- Dist))
+ if (!chooseBestLEA(Insns->second, MI, DefMI, AddrDispShift, Dist))
continue;
// If LEA occurs before current instruction, we can freely replace