From dee83c90bb7bda57f6d0db2d8f9138f411ecdbbc Mon Sep 17 00:00:00 2001
From: Jakob Stoklund Olesen <stoklund@2pi.dk>
Date: Wed, 12 Oct 2011 23:37:40 +0000
Subject: [PATCH] Also inflate register classes around inline asm.

Now that MI->getRegClassConstraint() can also handle inline assembly,
don't bail when recomputing the register class of a virtual register
used by inline asm.

This fixes PR11078.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141836 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/MachineRegisterInfo.cpp |  5 +----
 test/CodeGen/X86/crash.ll           | 27 +++++++++++++++++++++++++++
 2 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/lib/CodeGen/MachineRegisterInfo.cpp b/lib/CodeGen/MachineRegisterInfo.cpp
index 97d9d0f922c..266ebf64a3f 100644
--- a/lib/CodeGen/MachineRegisterInfo.cpp
+++ b/lib/CodeGen/MachineRegisterInfo.cpp
@@ -79,11 +79,8 @@ MachineRegisterInfo::recomputeRegClass(unsigned Reg, const TargetMachine &TM) {
     // TRI doesn't have accurate enough information to model this yet.
     if (I.getOperand().getSubReg())
       return false;
-    // Inline asm instuctions don't remember their constraints.
-    if (I->isInlineAsm())
-      return false;
     const TargetRegisterClass *OpRC =
-      TII->getRegClass(I->getDesc(), I.getOperandNo(), TRI);
+      I->getRegClassConstraint(I.getOperandNo(), TII, TRI);
     if (OpRC)
       NewRC = TRI->getCommonSubClass(NewRC, OpRC);
     if (!NewRC || NewRC == OldRC)
diff --git a/test/CodeGen/X86/crash.ll b/test/CodeGen/X86/crash.ll
index 6f4bf6d31fa..153145728f5 100644
--- a/test/CodeGen/X86/crash.ll
+++ b/test/CodeGen/X86/crash.ll
@@ -364,3 +364,30 @@ entry:
 "5":
   ret void
 }
+
+; PR11078
+;
+; A virtual register used by the "foo" inline asm memory operand gets
+; constrained to GR32_ABCD during coalescing.  This makes the inline asm
+; impossible to allocate without splitting the live range and reinflating the
+; register class around the inline asm.
+;
+; The constraint originally comes from the TEST8ri optimization of (icmp (and %t0, 1), 0).
+
+@__force_order = external hidden global i32, align 4
+define void @pr11078(i32* %pgd) nounwind {
+entry:
+  %t0 = load i32* %pgd, align 4
+  %and2 = and i32 %t0, 1
+  %tobool = icmp eq i32 %and2, 0
+  br i1 %tobool, label %if.then, label %if.end
+
+if.then:
+  %t1 = tail call i32 asm sideeffect "bar", "=r,=*m,~{dirflag},~{fpsr},~{flags}"(i32* @__force_order) nounwind
+  br label %if.end
+
+if.end:
+  %t6 = inttoptr i32 %t0 to i64*
+  %t11 = tail call i64 asm sideeffect "foo", "=*m,=A,{bx},{cx},1,~{memory},~{dirflag},~{fpsr},~{flags}"(i64* %t6, i32 0, i32 0, i64 0) nounwind
+  ret void
+}