Merging r263139:

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r263139 | michael.kuperstein | 2016-03-10 10:43:21 -0800 (Thu, 10 Mar 2016) | 12 lines

[X86] Correctly select registers to pop into for x86_64

When trying to replace an add to esp with pops, we need to choose dead
registers to pop into. Registers clobbered by the call and not imp-def'd
by it should be safe. Except that it's not enough to check the register
itself isn't defined, we also need to make sure no overlapping registers
are defined either.

This fixes PR26711.

Differential Revision: http://reviews.llvm.org/D18029

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_38@269657 91177308-0d34-0410-b5e6-96231b3b80d8

Author: tstellarAMD

lib/Target/X86/X86FrameLowering.cpp

@@ -2440,7 +2440,9 @@ bool X86FrameLowering::adjustStackWithPops(MachineBasicBlock &MBB,
 
     bool IsDef = false;
     for (const MachineOperand &MO : Prev->implicit_operands()) {
-      if (MO.isReg() && MO.isDef() && MO.getReg() == Candidate) {
+      if (MO.isReg() && MO.isDef() &&
+          (TRI->isSubRegisterEq(MO.getReg(), Candidate) ||
+           TRI->isSuperRegister(MO.getReg(), Candidate))) {
         IsDef = true;
         break;
       }

test/CodeGen/X86/pop-stack-cleanup.ll

@@ -7,6 +7,7 @@ declare i64 @param2_ret64(i32 %a, i32 %b)
 declare void @param2(i32 %a, i32 %b)
 declare void @param3(i32 %a, i32 %b, i32 %c)
 declare void @param8(i64, i64, i64, i64, i64, i64, i64, i64)
+declare i32 @param8_ret(i64, i64, i64, i64, i64, i64, i64, i64)
 
 
 define void @test() minsize nounwind {
@@ -74,3 +75,13 @@ define void @test_linux64(i32 %size) minsize nounwind {
   call void @param8(i64 1, i64 2, i64 3, i64 4, i64 5, i64 6, i64 7, i64 8)
   ret void
 }
+
+define i32 @test_linux64_i32(i32 %size) minsize nounwind {
+; LINUX64-LABEL: test_linux64_i32:
+; LINUX64: callq param8_ret
+; LINUX64-NOT: popq %rax
+; LINUX64: retq
+  %a = alloca i64, i32 %size, align 8
+  %r = call i32 @param8_ret(i64 1, i64 2, i64 3, i64 4, i64 5, i64 6, i64 7, i64 8)
+  ret i32 %r
+}