[PATCH] D51991: [WebAssembly] Make tied inline asm operands work again

[Heejin Ahn via Phabricator via llvm-commits]

aheejin created this revision.
aheejin added a reviewer: sunfish.
Herald added subscribers: llvm-commits, eraman, jgravelle-google, sbc100, dschuff.

https://reviews.llvm.org/rL341389 broke code with tied register operands in inline assembly. For
example, `asm("" : "=r"(var) : "0"(var));`
The code above specifies the input operand to be in the same register
with the output operand, tying the two register. This patch makes this
kind of code work again.


Repository:
  rL LLVM

https://reviews.llvm.org/D51991

Files:
  lib/Target/WebAssembly/WebAssemblyExplicitLocals.cpp
  test/CodeGen/WebAssembly/inline-asm.ll


Index: test/CodeGen/WebAssembly/inline-asm.ll
===================================================================
--- test/CodeGen/WebAssembly/inline-asm.ll
+++ test/CodeGen/WebAssembly/inline-asm.ll
@@ -97,6 +97,15 @@
   ret i32 %t0
 }
 
+; CHECK-LABEL: tied_operands
+; CHECK: get_local  $push0=, 0
+; CHECK: return    $pop0
+define i32 @tied_operands(i32 %var) {
+entry:
+  %ret = call i32 asm "", "=r,0"(i32 %var)
+  ret i32 %ret
+}
+
 attributes #0 = { nounwind }
 
 !0 = !{i32 47}
Index: lib/Target/WebAssembly/WebAssemblyExplicitLocals.cpp
===================================================================
--- lib/Target/WebAssembly/WebAssemblyExplicitLocals.cpp
+++ lib/Target/WebAssembly/WebAssemblyExplicitLocals.cpp
@@ -316,6 +316,7 @@
         if (MO.isDef()) {
           assert(MI.getOpcode() == TargetOpcode::INLINEASM);
           unsigned LocalId = getLocalId(Reg2Local, CurLocal, OldReg);
+          MI.untieRegOperand(MI.getOperandNo(&MO));
           MO.ChangeToImmediate(LocalId);
           continue;
         }
@@ -331,6 +332,7 @@
         // indices as immediates.
         if (MI.getOpcode() == TargetOpcode::INLINEASM) {
           unsigned LocalId = getLocalId(Reg2Local, CurLocal, OldReg);
+          MI.untieRegOperand(MI.getOperandNo(&MO));
           MO.ChangeToImmediate(LocalId);
           continue;
         }


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