The AND instruction leaves the V flag unmodified, so it falls victim to the same

problem as all of the other instructions we fold with CMPs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129602 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/ARM/ARMBaseInstrInfo.cpp b/lib/Target/ARM/ARMBaseInstrInfo.cpp
index e2eeeed..465d612 100644 (file)
--- a/lib/Target/ARM/ARMBaseInstrInfo.cpp
+++ b/lib/Target/ARM/ARMBaseInstrInfo.cpp
@@ -1638,7 +1638,11 @@ OptimizeCompareInstr(MachineInstr *CmpInstr, unsigned SrcReg, int CmpMask,
   case ARM::t2SUBrr:
   case ARM::t2SUBri:
   case ARM::t2SBCrr:
-  case ARM::t2SBCri: {
+  case ARM::t2SBCri:
+  case ARM::ANDrr:
+  case ARM::ANDri:
+  case ARM::t2ANDrr:
+  case ARM::t2ANDri: {
     // Scan forward for the use of CPSR, if it's a conditional code requires
     // checking of V bit, then this is not safe to do. If we can't find the
     // CPSR use (i.e. used in another block), then it's not safe to perform
@@ -1677,18 +1681,13 @@ OptimizeCompareInstr(MachineInstr *CmpInstr, unsigned SrcReg, int CmpMask,
     if (!isSafe)
       return false;
 
-    // fallthrough
-  }
-  case ARM::ANDrr:
-  case ARM::ANDri:
-  case ARM::t2ANDrr:
-  case ARM::t2ANDri:
     // Toggle the optional operand to CPSR.
     MI->getOperand(5).setReg(ARM::CPSR);
     MI->getOperand(5).setIsDef(true);
     CmpInstr->eraseFromParent();
     return true;
   }
+  }
 
   return false;
 }

diff --git a/test/CodeGen/ARM/2011-04-15-AndVFlagPeepholeBug.ll b/test/CodeGen/ARM/2011-04-15-AndVFlagPeepholeBug.ll
new file mode 100644 (file)
index 0000000..e712e08
--- /dev/null
+++ b/test/CodeGen/ARM/2011-04-15-AndVFlagPeepholeBug.ll
@@ -0,0 +1,22 @@
+; RUN: llc < %s -mtriple=thumbv7-apple-darwin10 | FileCheck %s
+
+; CHECK: _f
+; CHECK-NOT: ands
+; CHECK: cmp
+; CHECK: blxle _g
+
+define i32 @f(i32 %a, i32 %b) nounwind ssp {
+entry:
+  %and = and i32 %b, %a
+  %cmp = icmp slt i32 %and, 1
+  br i1 %cmp, label %if.then, label %if.end
+
+if.then:                                          ; preds = %entry
+  tail call void (...)* @g(i32 %a, i32 %b) nounwind
+  br label %if.end
+
+if.end:                                           ; preds = %if.then, %entry
+  ret i32 %and
+}
+
+declare void @g(...)