[PATCH] [AArch64] Type conversion bug when anlyze compare

[Xu Jiangwei]

http://reviews.llvm.org/D4771

Files:
  lib/Target/AArch64/AArch64InstrInfo.cpp
  test/CodeGen/AArch64/analyzecmp.ll

Index: lib/Target/AArch64/AArch64InstrInfo.cpp
===================================================================
--- lib/Target/AArch64/AArch64InstrInfo.cpp
+++ lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -649,9 +649,13 @@
     SrcReg = MI->getOperand(1).getReg();
     SrcReg2 = 0;
     CmpMask = ~0;
-    CmpValue = AArch64_AM::decodeLogicalImmediate(
-        MI->getOperand(2).getImm(),
-        MI->getOpcode() == AArch64::ANDSWri ? 32 : 64);
+    // 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;
   }
 
@@ -738,6 +742,8 @@
   }
 
   // Continue only if we have a "ri" where immediate is zero.
+  // CmpValue of ANDSWri and ANDSXri has already been converted to 0 or 1 in 
+  // analyzeCompare function.
   if (CmpValue != 0 || SrcReg2 != 0)
     return false;
 
Index: test/CodeGen/AArch64/analyzecmp.ll
===================================================================
--- /dev/null
+++ test/CodeGen/AArch64/analyzecmp.ll
@@ -0,0 +1,35 @@
+; 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 i64 @test(i64 %a) #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
+  %add.ptr.sum = add i64 %div, -1
+  br label %exit
+
+exit:                 
+  %add.ptr.sum.pn = phi i64 [ %add.ptr.sum, %if.then ], [ %div, %entry ]
+  %__n.0 = phi i64 [ %add2, %if.then ], [ %rem, %entry ]
+  %storemerge = getelementptr inbounds i64* null, i64 %add.ptr.sum.pn
+  %conv4.mask = and i64 %__n.0, 4294967295
+  %shl.i.i = shl i64 1, %conv4.mask
+  %0 = load i64* %storemerge, align 8
+  %and.i = and i64 %shl.i.i, %0
+  ret  i64 %and.i  
+}
+
+
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