Prevent obscure and incorrect tail-call optimization.

In this instance we are generating the tail-call during legalizeDAG.  The 2nd
floor call can't be a tail call because it clobbers %xmm1, which is defined by
the first floor call.  The first floor call can't be a tail-call because it's
not in the tail position.  The only reasonable way I could think to fix this
in a target-independent manner was to check for glue logic on the copy reg.

rdar://10930395

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151877 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 4ad179ead669dcc611571770777fe69e1f3d4175..d1ded33384973332483329d33cadd9d6f2e047d6 100644 (file)
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -1589,6 +1589,11 @@ bool X86TargetLowering::isUsedByReturnOnly(SDNode *N) const {
       Copy->getOpcode() != ISD::FP_EXTEND)
     return false;
 
+  // If anything is glued to the copy, then we can't safely perform a tail call.
+  if (Copy->getOpcode() == ISD::CopyToReg &&
+      Copy->getNumOperands() == 4)
+    return false;
+
   bool HasRet = false;
   for (SDNode::use_iterator UI = Copy->use_begin(), UE = Copy->use_end();
        UI != UE; ++UI) {

diff --git a/test/CodeGen/X86/sibcall-5.ll b/test/CodeGen/X86/sibcall-5.ll
index 9d74121b4301121a29b34823043cf180ec5b7d3c..937817e45647b2f2362a2177399bad9c99e006fe 100644 (file)
--- a/test/CodeGen/X86/sibcall-5.ll
+++ b/test/CodeGen/X86/sibcall-5.ll
@@ -1,5 +1,6 @@
 ; RUN: llc < %s -mtriple=i386-apple-darwin8 -mattr=+sse2  | FileCheck %s --check-prefix=X32
 ; RUN: llc < %s -mtriple=x86_64-apple-darwin -mattr=+sse2 | FileCheck %s --check-prefix=X64
+; RUN: llc < %s -mtriple=x86_64-apple-darwin -mattr=-sse3 | FileCheck %s --check-prefix=X64_BAD
 
 ; Sibcall optimization of expanded libcalls.
 ; rdar://8707777
@@ -29,3 +30,31 @@ entry:
 declare float @sinf(float) nounwind readonly
 
 declare double @sin(double) nounwind readonly
+
+; rdar://10930395
+%0 = type opaque
+
+@"\01L_OBJC_SELECTOR_REFERENCES_2" = external hidden global i8*, section "__DATA, __objc_selrefs, literal_pointers, no_dead_strip"
+
+define hidden { double, double } @foo2(%0* %self, i8* nocapture %_cmd) uwtable optsize ssp {
+; X64_BAD: foo
+; X64_BAD: call
+; X64_BAD: call
+; X64_BAD: call
+  %1 = load i8** @"\01L_OBJC_SELECTOR_REFERENCES_2", align 8, !invariant.load !0
+  %2 = bitcast %0* %self to i8*
+  %3 = tail call { double, double } bitcast (i8* (i8*, i8*, ...)* @objc_msgSend to { double, double } (i8*, i8*)*)(i8* %2, i8* %1) optsize
+  %4 = extractvalue { double, double } %3, 0
+  %5 = extractvalue { double, double } %3, 1
+  %6 = tail call double @floor(double %4) optsize
+  %7 = tail call double @floor(double %5) optsize
+  %insert.i.i = insertvalue { double, double } undef, double %6, 0
+  %insert5.i.i = insertvalue { double, double } %insert.i.i, double %7, 1
+  ret { double, double } %insert5.i.i
+}
+
+declare i8* @objc_msgSend(i8*, i8*, ...)
+
+declare double @floor(double) optsize
+
+!0 = metadata !{}