[llvm] r323539 - [DAG] Teach findBaseOffset to interpret indexes of indexed memory operations

[Nirav Dave via llvm-commits]

Author: niravd
Date: Fri Jan 26 08:51:27 2018
New Revision: 323539

URL: http://llvm.org/viewvc/llvm-project?rev=323539&view=rev
Log:
[DAG] Teach findBaseOffset to interpret indexes of indexed memory operations

Indexed outputs are addition / subtractions and can be interpreted as such.

Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp
    llvm/trunk/test/CodeGen/AArch64/arm64-abi-varargs.ll
    llvm/trunk/test/CodeGen/AArch64/swifterror.ll

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp?rev=323539&r1=323538&r2=323539&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp Fri Jan 26 08:51:27 2018
@@ -99,16 +99,43 @@ BaseIndexOffset BaseIndexOffset::match(L
   }
 
   // Consume constant adds & ors with appropriate masking.
-  while (Base->getOpcode() == ISD::ADD || Base->getOpcode() == ISD::OR) {
-    if (auto *C = dyn_cast<ConstantSDNode>(Base->getOperand(1))) {
+  while (true) {
+    switch (Base->getOpcode()) {
+    case ISD::OR:
       // Only consider ORs which act as adds.
-      if (Base->getOpcode() == ISD::OR &&
-          !DAG.MaskedValueIsZero(Base->getOperand(0), C->getAPIntValue()))
-        break;
-      Offset += C->getSExtValue();
-      Base = Base->getOperand(0);
-      continue;
+      if (auto *C = dyn_cast<ConstantSDNode>(Base->getOperand(1)))
+        if (DAG.MaskedValueIsZero(Base->getOperand(0), C->getAPIntValue())) {
+          Offset += C->getSExtValue();
+          Base = Base->getOperand(0);
+          continue;
+        }
+      break;
+    case ISD::ADD:
+      if (auto *C = dyn_cast<ConstantSDNode>(Base->getOperand(1))) {
+        Offset += C->getSExtValue();
+        Base = Base->getOperand(0);
+        continue;
+      }
+      break;
+    case ISD::LOAD:
+    case ISD::STORE: {
+      auto *LSBase = cast<LSBaseSDNode>(Base.getNode());
+      unsigned int IndexResNo = (Base->getOpcode() == ISD::LOAD) ? 1 : 0;
+      if (LSBase->isIndexed() && Base.getResNo() == IndexResNo)
+        if (auto *C = dyn_cast<ConstantSDNode>(LSBase->getOffset())) {
+          auto Off = C->getSExtValue();
+          if (LSBase->getAddressingMode() == ISD::PRE_DEC ||
+              LSBase->getAddressingMode() == ISD::POST_DEC)
+            Offset -= Off;
+          else
+            Offset += Off;
+          Base = LSBase->getBasePtr();
+          continue;
+        }
+      break;
     }
+    }
+    // If we get here break out of the loop.
     break;
   }
 

Modified: llvm/trunk/test/CodeGen/AArch64/arm64-abi-varargs.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AArch64/arm64-abi-varargs.ll?rev=323539&r1=323538&r2=323539&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/AArch64/arm64-abi-varargs.ll (original)
+++ llvm/trunk/test/CodeGen/AArch64/arm64-abi-varargs.ll Fri Jan 26 08:51:27 2018
@@ -13,9 +13,8 @@ define void @fn9(i32* %a1, i32 %a2, i32
 ; CHECK: ldr {{w[0-9]+}}, [sp, #72]
 ; Second vararg
 ; CHECK: ldr {{w[0-9]+}}, [{{x[0-9]+}}], #8
-; CHECK: add {{x[0-9]+}}, {{x[0-9]+}}, #8
 ; Third vararg
-; CHECK: ldr {{w[0-9]+}}, [{{x[0-9]+}}]
+; CHECK: ldr {{w[0-9]+}}, [{{x[0-9]+}}], #8
   %1 = alloca i32, align 4
   %2 = alloca i32, align 4
   %3 = alloca i32, align 4

Modified: llvm/trunk/test/CodeGen/AArch64/swifterror.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AArch64/swifterror.ll?rev=323539&r1=323538&r2=323539&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/AArch64/swifterror.ll (original)
+++ llvm/trunk/test/CodeGen/AArch64/swifterror.ll Fri Jan 26 08:51:27 2018
@@ -316,12 +316,11 @@ define float @foo_vararg(%swift_error**
 ; First vararg
 ; CHECK-APPLE-DAG: orr {{x[0-9]+}}, [[ARGS]], #0x8
 ; CHECK-APPLE-DAG: ldr {{w[0-9]+}}, [{{.*}}[[TMP]], #16]
-; CHECK-APPLE-DAG: add {{x[0-9]+}}, {{x[0-9]+}}, #8
 ; Second vararg
 ; CHECK-APPLE-DAG: ldr {{w[0-9]+}}, [{{x[0-9]+}}], #8
 ; CHECK-APPLE-DAG: add {{x[0-9]+}}, {{x[0-9]+}}, #16
 ; Third vararg
-; CHECK-APPLE: ldr {{w[0-9]+}}, [{{x[0-9]+}}]
+; CHECK-APPLE: ldr {{w[0-9]+}}, [{{x[0-9]+}}], #8
 
 ; CHECK-APPLE: mov x21, x0
 ; CHECK-APPLE-NOT: x21