[llvm] r338665 - Fix FCOPYSIGN expansion

[Lei Liu via llvm-commits]

Author: lliu0
Date: Wed Aug  1 18:54:12 2018
New Revision: 338665

URL: http://llvm.org/viewvc/llvm-project?rev=338665&view=rev
Log:
Fix FCOPYSIGN expansion

In expansion of FCOPYSIGN, the shift node is missing when the two
operands of FCOPYSIGN are of the same size. We should always generate
shift node (if the required shift bit is not zero) to put the sign
bit into the right position, regardless of the size of underlying
types.

Differential Revision: https://reviews.llvm.org/D49973


Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
    llvm/trunk/test/CodeGen/AArch64/fcopysign.ll

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp?rev=338665&r1=338664&r2=338665&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp Wed Aug  1 18:54:12 2018
@@ -1489,24 +1489,20 @@ SDValue SelectionDAGLegalize::ExpandFCOP
 
   // Get the signbit at the right position for MagAsInt.
   int ShiftAmount = SignAsInt.SignBit - MagAsInt.SignBit;
+  EVT ShiftVT = IntVT;
+  if (SignBit.getValueSizeInBits() < ClearedSign.getValueSizeInBits()) {
+    SignBit = DAG.getNode(ISD::ZERO_EXTEND, DL, MagVT, SignBit);
+    ShiftVT = MagVT;
+  }
+  if (ShiftAmount > 0) {
+    SDValue ShiftCnst = DAG.getConstant(ShiftAmount, DL, ShiftVT);
+    SignBit = DAG.getNode(ISD::SRL, DL, ShiftVT, SignBit, ShiftCnst);
+  } else if (ShiftAmount < 0) {
+    SDValue ShiftCnst = DAG.getConstant(-ShiftAmount, DL, ShiftVT);
+    SignBit = DAG.getNode(ISD::SHL, DL, ShiftVT, SignBit, ShiftCnst);
+  }
   if (SignBit.getValueSizeInBits() > ClearedSign.getValueSizeInBits()) {
-    if (ShiftAmount > 0) {
-      SDValue ShiftCnst = DAG.getConstant(ShiftAmount, DL, IntVT);
-      SignBit = DAG.getNode(ISD::SRL, DL, IntVT, SignBit, ShiftCnst);
-    } else if (ShiftAmount < 0) {
-      SDValue ShiftCnst = DAG.getConstant(-ShiftAmount, DL, IntVT);
-      SignBit = DAG.getNode(ISD::SHL, DL, IntVT, SignBit, ShiftCnst);
-    }
     SignBit = DAG.getNode(ISD::TRUNCATE, DL, MagVT, SignBit);
-  } else if (SignBit.getValueSizeInBits() < ClearedSign.getValueSizeInBits()) {
-    SignBit = DAG.getNode(ISD::ZERO_EXTEND, DL, MagVT, SignBit);
-    if (ShiftAmount > 0) {
-      SDValue ShiftCnst = DAG.getConstant(ShiftAmount, DL, MagVT);
-      SignBit = DAG.getNode(ISD::SRL, DL, MagVT, SignBit, ShiftCnst);
-    } else if (ShiftAmount < 0) {
-      SDValue ShiftCnst = DAG.getConstant(-ShiftAmount, DL, MagVT);
-      SignBit = DAG.getNode(ISD::SHL, DL, MagVT, SignBit, ShiftCnst);
-    }
   }
 
   // Store the part with the modified sign and convert back to float.

Modified: llvm/trunk/test/CodeGen/AArch64/fcopysign.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AArch64/fcopysign.ll?rev=338665&r1=338664&r2=338665&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/AArch64/fcopysign.ll (original)
+++ llvm/trunk/test/CodeGen/AArch64/fcopysign.ll Wed Aug  1 18:54:12 2018
@@ -5,10 +5,12 @@ target triple = "aarch64--"
 
 declare fp128 @llvm.copysign.f128(fp128, fp128)
 
- at val = global double zeroinitializer, align 8
+ at val_float = global float zeroinitializer, align 4
+ at val_double = global double zeroinitializer, align 8
+ at val_fp128 = global fp128 zeroinitializer, align 16
 
 ; CHECK-LABEL: copysign0
-; CHECK: ldr [[REG:x[0-9]+]], [x8, :lo12:val]
+; CHECK: ldr [[REG:x[0-9]+]], [x8, :lo12:val_double]
 ; CHECK: and [[ANDREG:x[0-9]+]], [[REG]], #0x8000000000000000
 ; CHECK: lsr x[[LSRREGNUM:[0-9]+]], [[ANDREG]], #56
 ; CHECK: bfxil w[[LSRREGNUM]], w{{[0-9]+}}, #0, #7
@@ -16,8 +18,25 @@ declare fp128 @llvm.copysign.f128(fp128,
 ; CHECK: ldr q{{[0-9]+}},
 define fp128 @copysign0() {
 entry:
-  %v = load double, double* @val, align 8
+  %v = load double, double* @val_double, align 8
   %conv = fpext double %v to fp128
   %call = tail call fp128 @llvm.copysign.f128(fp128 0xL00000000000000007FFF000000000000, fp128 %conv) #2
   ret fp128 %call
 }
+
+; CHECK-LABEL: copysign1
+; CHECK-DAG: ldr [[REG:q[0-9]+]], [x8, :lo12:val_fp128]
+; CHECK-DAG: ldr [[REG:w[0-9]+]], [x8, :lo12:val_float]
+; CHECK: and [[ANDREG:w[0-9]+]], [[REG]], #0x80000000
+; CHECK: lsr w[[LSRREGNUM:[0-9]+]], [[ANDREG]], #24
+; CHECK: bfxil w[[LSRREGNUM]], w{{[0-9]+}}, #0, #7
+; CHECK: strb w[[LSRREGNUM]],
+; CHECK: ldr q{{[0-9]+}},
+define fp128 at copysign1() {
+entry:
+  %v0 = load fp128, fp128* @val_fp128, align 16
+  %v1 = load float, float* @val_float, align 4
+  %conv = fpext float %v1 to fp128
+  %call = tail call fp128 @llvm.copysign.f128(fp128 %v0, fp128 %conv)
+  ret fp128 %call
+}