[PATCH] D49984: Fix uninitialized read in ARM's PrintAsmOperand

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

thopre created this revision.
thopre added reviewers: t.p.northover, weimingz.
Herald added a reviewer: javed.absar.
Herald added subscribers: chrib, kristof.beyls, eraman.

Fix read of uninitialized RC variable in ARM's PrintAsmOperand when
hasRegClassConstraint returns false. This was causing
inline-asm-operand-implicit-cast test to fail in r338206.


Repository:
  rL LLVM

https://reviews.llvm.org/D49984

Files:
  lib/Target/ARM/ARMAsmPrinter.cpp
  test/CodeGen/ARM/inlineasm-64bit.ll


Index: test/CodeGen/ARM/inlineasm-64bit.ll
===================================================================
--- test/CodeGen/ARM/inlineasm-64bit.ll
+++ test/CodeGen/ARM/inlineasm-64bit.ll
@@ -104,3 +104,11 @@
   %res = extractvalue {i64, i32, i64} %vars, 2
   ret i64 %res
 }
+
+; Check access to low and high part with a specific register pair constraint
+define i64 @low_high_specific_reg_pair(i64 %in) nounwind {
+; CHECK-LABEL: low_high_specific_reg_pair
+; CHECK: mov r3, r2
+  %res = call i64 asm "mov ${0:R}, ${1:Q}", "=&{r2},0"(i64 %in)
+  ret i64 %res
+}
Index: lib/Target/ARM/ARMAsmPrinter.cpp
===================================================================
--- lib/Target/ARM/ARMAsmPrinter.cpp
+++ lib/Target/ARM/ARMAsmPrinter.cpp
@@ -367,8 +367,9 @@
 
       unsigned NumVals = InlineAsm::getNumOperandRegisters(Flags);
       unsigned RC;
-      InlineAsm::hasRegClassConstraint(Flags, RC);
-      if (RC == ARM::GPRPairRegClassID) {
+      const TargetRegisterInfo *TRI = MF->getSubtarget().getRegisterInfo();
+      if (InlineAsm::hasRegClassConstraint(Flags, RC) &&
+          ARM::GPRPairRegClass.hasSubClassEq(TRI->getRegClass(RC))) {
         if (NumVals != 1)
           return true;
         const MachineOperand &MO = MI->getOperand(OpNum);


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D49984.157953.patch
Type: text/x-patch
Size: 1270 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20180730/72cd07f7/attachment.bin>