[AArch64] Fix a type conversion bug for anlyzing compare.

The bug can cause spec2006/483.xalancbmk failure.

Patched by David Xu.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215206 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/AArch64/AArch64InstrInfo.cpp b/lib/Target/AArch64/AArch64InstrInfo.cpp
index 1ee84f927eecb4f728e6ccbf869c6392d1901c6d..80aa9b5413a803c8bd3a79d97123cfc0d5e9db73 100644 (file)
--- a/lib/Target/AArch64/AArch64InstrInfo.cpp
+++ b/lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -641,7 +641,8 @@ bool AArch64InstrInfo::analyzeCompare(const MachineInstr *MI, unsigned &SrcReg,
     SrcReg = MI->getOperand(1).getReg();
     SrcReg2 = 0;
     CmpMask = ~0;
-    CmpValue = MI->getOperand(2).getImm();
+    // FIXME: In order to convert CmpValue to 0 or 1
+    CmpValue = (MI->getOperand(2).getImm() != 0);
     return true;
   case AArch64::ANDSWri:
   case AArch64::ANDSXri:
@@ -650,9 +651,14 @@ bool AArch64InstrInfo::analyzeCompare(const MachineInstr *MI, unsigned &SrcReg,
     SrcReg = MI->getOperand(1).getReg();
     SrcReg2 = 0;
     CmpMask = ~0;
-    CmpValue = AArch64_AM::decodeLogicalImmediate(
-        MI->getOperand(2).getImm(),
-        MI->getOpcode() == AArch64::ANDSWri ? 32 : 64);
+    // FIXME:The return val type of decodeLogicalImmediate is uint64_t,
+    // while the type of CmpValue is int. When converting uint64_t to int,
+    // the high 32 bits of uint64_t will be lost.
+    // In fact it causes a bug in spec2006-483.xalancbmk
+    // CmpValue is only used to compare with zero in OptimizeCompareInstr
+    CmpValue = (AArch64_AM::decodeLogicalImmediate(
+                    MI->getOperand(2).getImm(),
+                    MI->getOpcode() == AArch64::ANDSWri ? 32 : 64) != 0);
     return true;
   }
 
@@ -749,6 +755,9 @@ bool AArch64InstrInfo::optimizeCompareInstr(
   }
 
   // Continue only if we have a "ri" where immediate is zero.
+  // FIXME:CmpValue has already been converted to 0 or 1 in analyzeCompare
+  // function.
+  assert((CmpValue == 0 || CmpValue == 1) && "CmpValue must be 0 or 1!");
   if (CmpValue != 0 || SrcReg2 != 0)
     return false;
 

diff --git a/test/CodeGen/AArch64/analyzecmp.ll b/test/CodeGen/AArch64/analyzecmp.ll
new file mode 100644 (file)
index 0000000..8962505
--- /dev/null
+++ b/test/CodeGen/AArch64/analyzecmp.ll
@@ -0,0 +1,32 @@
+; RUN: llc -O3 -mcpu=cortex-a57 < %s | FileCheck %s 
+
+; CHECK-LABLE: @test
+; CHECK: tst [[CMP:x[0-9]+]], #0x8000000000000000
+; CHECK: csel [[R0:x[0-9]+]], [[S0:x[0-9]+]], [[S1:x[0-9]+]], eq
+; CHECK: csel [[R1:x[0-9]+]], [[S2:x[0-9]+]], [[S3:x[0-9]+]], eq
+target datalayout = "e-m:e-i64:64-i128:128-n32:64-S128"
+target triple = "arm64--linux-gnueabi"
+
+define void @test(i64 %a, i64* %ptr1, i64* %ptr2) #0 align 2 {
+entry:
+  %conv = and i64 %a, 4294967295
+  %add = add nsw i64 %conv, -1
+  %div = sdiv i64 %add, 64
+  %rem = srem i64 %add, 64
+  %cmp = icmp slt i64 %rem, 0
+  br i1 %cmp, label %if.then, label %exit
+
+if.then:                                
+  %add2 = add nsw i64 %rem, 64
+  %add3 = add i64 %div, -1
+  br label %exit
+
+exit:                 
+  %__n = phi i64 [ %add3, %if.then ], [ %div, %entry ]
+  %__n.0 = phi i64 [ %add2, %if.then ], [ %rem, %entry ]
+  store i64 %__n, i64* %ptr1
+  store i64 %__n.0, i64* %ptr2
+  ret void 
+}
+
+