[PATCH] D45376: Fix PR34170: Crash on inline asm with 64bit output in 32bit GPR

[Thomas Preud'homme via Phabricator via llvm-commits]

thopre updated this revision to Diff 152299.
thopre added a comment.
Herald added a reviewer: javed.absar.

Split the matching input handling into a separate patch.


Repository:
  rL LLVM

https://reviews.llvm.org/D45376

Files:
  lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
  test/CodeGen/ARM/pr34170.ll


Index: test/CodeGen/ARM/pr34170.ll
===================================================================
--- /dev/null
+++ test/CodeGen/ARM/pr34170.ll
@@ -0,0 +1,13 @@
+; RUN: llc -mtriple armv7-arm-linux-gnueabihf -O2 -mcpu=cortex-a7 < %s | FileCheck %s
+
+; Check support for returning a double in GPR
+define double @zerobits_double() #0 {
+; CHECK-LABEL: zerobits_double
+; CHECK: mov r0, #0
+; CHECK-NEXT: mov r1, #0
+; CHECK: vmov d0, r0, r1
+  %1 = tail call double asm "mov ${0:Q}, #0\0Amov ${0:R}, #0", "=&r"()
+  ret double %1
+}
+
+attributes #0 = { nounwind "target-features"="+d16,+vfp2,+vfp3,-fp-only-sp" }
Index: lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -7142,27 +7142,37 @@
 
   unsigned NumRegs = 1;
   if (OpInfo.ConstraintVT != MVT::Other) {
-    // If this is a FP input in an integer register (or visa versa) insert a bit
-    // cast of the input value.  More generally, handle any case where the input
-    // value disagrees with the register class we plan to stick this in.
-    if (OpInfo.Type == InlineAsm::isInput && PhysReg.second &&
+    // If this is a FP operand in an integer register (or visa versa), or more
+    // generally if the operand value disagrees with the register class we plan
+    // to stick it in, fix the operand type.
+    //
+    // If this is an input value, the bitcast to the new type is done now.
+    // Bitcast for output value is done at the end of visitInlineAsm().
+    if ((OpInfo.Type == InlineAsm::isOutput ||
+         OpInfo.Type == InlineAsm::isInput) &&
+        PhysReg.second &&
         !TRI.isTypeLegalForClass(*PhysReg.second, OpInfo.ConstraintVT)) {
       // Try to convert to the first EVT that the reg class contains.  If the
       // types are identical size, use a bitcast to convert (e.g. two differing
-      // vector types).
+      // vector types).  Note: output bitcast is done at the end of
+      // visitInlineAsm().
       MVT RegVT = *TRI.legalclasstypes_begin(*PhysReg.second);
-      if (RegVT.getSizeInBits() == OpInfo.CallOperand.getValueSizeInBits()) {
-        OpInfo.CallOperand = DAG.getNode(ISD::BITCAST, DL,
-                                         RegVT, OpInfo.CallOperand);
+      if (RegVT.getSizeInBits() == OpInfo.ConstraintVT.getSizeInBits()) {
+        // Exclude indirect inputs while they are unsupported because the code
+        // to perform the load is missing and thus OpInfo.CallOperand still
+        // refer to the input address rather than the pointed-to value.
+        if (OpInfo.Type == InlineAsm::isInput && !OpInfo.isIndirect)
+          OpInfo.CallOperand =
+              DAG.getNode(ISD::BITCAST, DL, RegVT, OpInfo.CallOperand);
         OpInfo.ConstraintVT = RegVT;
+        // If the operand is a FP value and we want it in integer registers,
+        // use the corresponding integer type. This turns an f64 value into
+        // i64, which can be passed with two i32 values on a 32-bit machine.
       } else if (RegVT.isInteger() && OpInfo.ConstraintVT.isFloatingPoint()) {
-        // If the input is a FP value and we want it in FP registers, do a
-        // bitcast to the corresponding integer type.  This turns an f64 value
-        // into i64, which can be passed with two i32 values on a 32-bit
-        // machine.
         RegVT = MVT::getIntegerVT(OpInfo.ConstraintVT.getSizeInBits());
-        OpInfo.CallOperand = DAG.getNode(ISD::BITCAST, DL,
-                                         RegVT, OpInfo.CallOperand);
+        if (OpInfo.Type == InlineAsm::isInput)
+          OpInfo.CallOperand =
+              DAG.getNode(ISD::BITCAST, DL, RegVT, OpInfo.CallOperand);
         OpInfo.ConstraintVT = RegVT;
       }
     }
@@ -7674,12 +7684,18 @@
     if (CS.getType()->isSingleValueType() && CS.getType()->isSized()) {
       EVT ResultType = TLI.getValueType(DAG.getDataLayout(), CS.getType());
 
-      // If any of the results of the inline asm is a vector, it may have the
-      // wrong width/num elts.  This can happen for register classes that can
-      // contain multiple different value types.  The preg or vreg allocated may
-      // not have the same VT as was expected.  Convert it to the right type
-      // with bit_convert.
-      if (ResultType != Val.getValueType() && Val.getValueType().isVector()) {
+      // If the type of the inline asm call site return value is different but
+      // has same size as the type of the asm output bitcast it.  One example
+      // of this is for vectors with different width / number of elements.
+      // This can happen for register classes that can contain multiple
+      // different value types.  The preg or vreg allocated may not have the
+      // same VT as was expected.
+      //
+      // This can also happen for a return value that disagrees with the
+      // register class it is put in, eg. a double in a general-purpose
+      // register on a 32-bit machine.
+      if (ResultType != Val.getValueType() &&
+          ResultType.getSizeInBits() == Val.getValueSizeInBits()) {
         Val = DAG.getNode(ISD::BITCAST, getCurSDLoc(),
                           ResultType, Val);
 


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D45376.152299.patch
Type: text/x-patch
Size: 5294 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20180621/b7017d15/attachment.bin>