[llvm] r337673 - [x86/SLH] Fix a bug where we would harden tail calls twice -- once as

[Chandler Carruth via llvm-commits]

Author: chandlerc
Date: Mon Jul 23 00:56:15 2018
New Revision: 337673

URL: http://llvm.org/viewvc/llvm-project?rev=337673&view=rev
Log:
[x86/SLH] Fix a bug where we would harden tail calls twice -- once as
a call, and then again as a return.

Also added a comment to try and explain better why we would be doing
what we're doing when hardening the (non-call) returns.

Modified:
    llvm/trunk/lib/Target/X86/X86SpeculativeLoadHardening.cpp
    llvm/trunk/test/CodeGen/X86/speculative-load-hardening-indirect.ll

Modified: llvm/trunk/lib/Target/X86/X86SpeculativeLoadHardening.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86SpeculativeLoadHardening.cpp?rev=337673&r1=337672&r2=337673&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86SpeculativeLoadHardening.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86SpeculativeLoadHardening.cpp Mon Jul 23 00:56:15 2018
@@ -525,7 +525,11 @@ bool X86SpeculativeLoadHardeningPass::ru
         continue;
 
       MachineInstr &MI = MBB.back();
-      if (!MI.isReturn())
+
+      // We only care about returns that are not also calls. For calls, that
+      // happen to also be returns (tail calls) we will have already handled
+      // them as calls.
+      if (!MI.isReturn() || MI.isCall())
         continue;
 
       hardenReturnInstr(MI);

Modified: llvm/trunk/test/CodeGen/X86/speculative-load-hardening-indirect.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/speculative-load-hardening-indirect.ll?rev=337673&r1=337672&r2=337673&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/speculative-load-hardening-indirect.ll (original)
+++ llvm/trunk/test/CodeGen/X86/speculative-load-hardening-indirect.ll Mon Jul 23 00:56:15 2018
@@ -37,9 +37,6 @@ define i32 @test_indirect_tail_call(i32
 ; X64-NEXT:    movq %rsp, %rax
 ; X64-NEXT:    movq $-1, %rcx
 ; X64-NEXT:    sarq $63, %rax
-; X64-NEXT:    movq %rax, %rcx
-; X64-NEXT:    shlq $47, %rcx
-; X64-NEXT:    orq %rcx, %rsp
 ; X64-NEXT:    shlq $47, %rax
 ; X64-NEXT:    orq %rax, %rsp
 ; X64-NEXT:    jmpq *(%rdi) # TAILCALL
@@ -77,9 +74,6 @@ define i32 @test_indirect_tail_call_glob
 ; X64-NEXT:    movq %rsp, %rax
 ; X64-NEXT:    movq $-1, %rcx
 ; X64-NEXT:    sarq $63, %rax
-; X64-NEXT:    movq %rax, %rcx
-; X64-NEXT:    shlq $47, %rcx
-; X64-NEXT:    orq %rcx, %rsp
 ; X64-NEXT:    shlq $47, %rax
 ; X64-NEXT:    orq %rax, %rsp
 ; X64-NEXT:    jmpq *{{.*}}(%rip) # TAILCALL