Fix fastcc structure return with fast-isel on x86-32

On x86-32, structure return via sret lets the callee pop the hidden
pointer argument off the stack, which the caller then re-pushes.
However if the calling convention is fastcc, then a register is used
instead, and the caller should not adjust the stack. This is
implemented with a check of IsTailCallConvention
X86TargetLowering::LowerCall but is now checked properly in
X86FastISel::DoSelectCall.

(this time, actually commit what was reviewed!)



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155825 91177308-0d34-0410-b5e6-96231b3b80d8

test/CodeGen/X86/fast-isel-x86.ll

@@ -46,3 +46,17 @@ entry:
 ; CHECK: addl $40
 }
 declare void @test3sret(%struct.a* sret)
+
+; Check that fast-isel sret works with fastcc (and does not callee-pop)
+define void @test4() nounwind ssp {
+entry:
+  %tmp = alloca %struct.a, align 8
+  call fastcc void @test4fastccsret(%struct.a* sret %tmp)
+  ret void
+; CHECK: test4:
+; CHECK: subl $28
+; CHECK: leal (%esp), %ecx
+; CHECK: calll _test4fastccsret
+; CHECK addl $28
+}
+declare fastcc void @test4fastccsret(%struct.a* sret)