[llvm-branch-commits] [llvm] 687b83c - [X86FastISel] Fix MO_GOTPCREL GlobalValue reference in static relocation model

[Fangrui Song via llvm-branch-commits]

Author: Fangrui Song
Date: 2020-12-05T23:13:28-08:00
New Revision: 687b83ceabafe81970cd4639e7f0c89036402081

URL: https://github.com/llvm/llvm-project/commit/687b83ceabafe81970cd4639e7f0c89036402081
DIFF: https://github.com/llvm/llvm-project/commit/687b83ceabafe81970cd4639e7f0c89036402081.diff

LOG: [X86FastISel] Fix MO_GOTPCREL GlobalValue reference in static relocation model

This fixes the bug referenced by 5582a7987662a92eda5d883b88fc4586e755acf5
which was exposed by 961f31d8ad14c66829991522d73e14b5a96ff6d4.

With this change, `movq src at GOTPCREL, %rcx` => `movq src at GOTPCREL(%rip), %rcx`

Added: 
    

Modified: 
    llvm/lib/Target/X86/X86FastISel.cpp
    llvm/test/CodeGen/X86/fast-isel-mem.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/X86/X86FastISel.cpp b/llvm/lib/Target/X86/X86FastISel.cpp
index a8db3d416c2e..caf158102230 100644
--- a/llvm/lib/Target/X86/X86FastISel.cpp
+++ b/llvm/lib/Target/X86/X86FastISel.cpp
@@ -784,7 +784,7 @@ bool X86FastISel::handleConstantAddresses(const Value *V, X86AddressMode &AM) {
           RC  = &X86::GR32RegClass;
         }
 
-        if (Subtarget->isPICStyleRIPRel())
+        if (Subtarget->isPICStyleRIPRel() || GVFlags == X86II::MO_GOTPCREL)
           StubAM.Base.Reg = X86::RIP;
 
         LoadReg = createResultReg(RC);

diff  --git a/llvm/test/CodeGen/X86/fast-isel-mem.ll b/llvm/test/CodeGen/X86/fast-isel-mem.ll
index 3f1d9cae9340..42f210199e64 100644
--- a/llvm/test/CodeGen/X86/fast-isel-mem.ll
+++ b/llvm/test/CodeGen/X86/fast-isel-mem.ll
@@ -1,7 +1,8 @@
 ; RUN: llc < %s -fast-isel -mtriple=i386-apple-darwin -mcpu=generic | FileCheck %s
 ; RUN: llc < %s -fast-isel -mtriple=i386-apple-darwin -mcpu=atom | FileCheck -check-prefix=ATOM %s
+; RUN: llc < %s -fast-isel -fast-isel-abort=3 -mtriple=x86_64 | FileCheck -check-prefix=ELF64 %s
 
- at src = external global i32
+ at src = external dso_preemptable global i32
 
 ; rdar://6653118
 define i32 @loadgv() nounwind {
@@ -26,6 +27,14 @@ entry:
 ; ATOM:         movl    %eax, (%ecx)
 ; ATOM:         ret
 
+;; dso_preemptable src is loaded via GOT indirection.
+; ELF64-LABEL: loadgv:
+; ELF64:        movq    src at GOTPCREL(%rip), %rcx
+; ELF64-NEXT:   movl    (%rcx), %eax
+; ELF64-NEXT:   addl    (%rcx), %eax
+; ELF64-NEXT:   movl    %eax, (%rcx)
+; ELF64-NEXT:   retq
+
 }
 
 %stuff = type { i32 (...)** }