[PATCH] D57677: [mips][micromips] Fix values in .gcc_except_table for -fPIC

Mon Feb 4 02:54:44 PST 2019

abeserminji created this revision.
abeserminji added reviewers: atanasyan, petarj.
Herald added subscribers: jrtc27, arichardson, sdardis.
Herald added a project: LLVM.

When a landing pad is calculated in a program that is compiled
for micromips with -fPIC flag, it will point to an even address.
Such an error will cause a segmentation fault, as the instructions
in micromips are aligned on odd addresses. This patch sets the
last bit of the offset where a landing pad is, to 1, which will
effectively be an odd address and point to the instruction exactly.

Patch D52985 <https://reviews.llvm.org/D52985> fixed this issue for -static compilation.


Repository:
  rL LLVM

https://reviews.llvm.org/D57677

Files:
  lib/MC/MCExpr.cpp
  test/CodeGen/Mips/micromips-b-range.ll
  test/DebugInfo/Mips/eh_frame.ll


Index: test/DebugInfo/Mips/eh_frame.ll
===================================================================

--- test/DebugInfo/Mips/eh_frame.ll
+++ test/DebugInfo/Mips/eh_frame.ll
@@ -1,9 +1,21 @@
-; RUN: llc -mtriple mips-unknown-linux-gnu -mattr=+micromips -O3 -filetype=obj -o - %s | llvm-readelf -r | FileCheck %s
-
-; CHECK: .rel.eh_frame
-; CHECK: DW.ref.__gxx_personality_v0
-; CHECK-NEXT: .text
-; CHECK-NEXT: .gcc_except_table
+; RUN: llc -mtriple mips-unknown-linux-gnu -mattr=+micromips -relocation-model=static -O3 -filetype=obj -o - %s | \
+; RUN:     llvm-readelf -r | FileCheck %s --check-prefix=CHECK-READELF
+; RUN: llc -mtriple mips-unknown-linux-gnu -mattr=+micromips -relocation-model=pic -O3 -filetype=obj -o - %s | \
+; RUN:     llvm-readelf -r | FileCheck %s --check-prefix=CHECK-READELF
+; RUN: llc -mtriple mips-unknown-linux-gnu -mattr=+micromips -relocation-model=static -O3 -filetype=obj -o - %s | \
+; RUN:     llvm-objdump -s -j .gcc_except_table - | FileCheck %s --check-prefix=CHECK-EXCEPT-TABLE-STATIC
+; RUN: llc -mtriple mips-unknown-linux-gnu -mattr=+micromips -relocation-model=pic -O3 -filetype=obj -o - %s | \
+; RUN:     llvm-objdump -s -j .gcc_except_table - | FileCheck %s --check-prefix=CHECK-EXCEPT-TABLE-PIC
+
+; CHECK-READELF: .rel.eh_frame
+; CHECK-READELF: DW.ref.__gxx_personality_v0
+; CHECK-READELF-NEXT: .text
+; CHECK-READELF-NEXT: .gcc_except_table
+
+; CHECK-EXCEPT-TABLE-STATIC: 0000 ff9b1501 0c011500 00150e23 01231e00  ...........#.#..
+; CHECK-EXCEPT-TABLE-STATIC: 0010 00010000 00000000
+; CHECK-EXCEPT-TABLE-PIC:    0000 ff9b1501 0c012d00 002d133f 013f2a00 ......-..-.?.?*.
+; CHECK-EXCEPT-TABLE-PIC:    0010 00010000 00000000                    ........
 
 @_ZTIi = external constant i8*
 
Index: test/CodeGen/Mips/micromips-b-range.ll
===================================================================
--- test/CodeGen/Mips/micromips-b-range.ll
+++ test/CodeGen/Mips/micromips-b-range.ll
@@ -13,7 +13,7 @@
 ; CHECK-NEXT:    1e:	fb fd 00 00 	sw	$ra, 0($sp)
 ; CHECK-NEXT:    22:	41 a1 00 01 	lui	$1, 1
 ; CHECK-NEXT:    26:	40 60 00 02 	bal	8 <foo+0x2e>
-; CHECK-NEXT:    2a:	30 21 04 68 	addiu	$1, $1, 1128
+; CHECK-NEXT:    2a:	30 21 04 69 	addiu	$1, $1, 1129
 ; CHECK-NEXT:    2e:	00 3f 09 50 	addu	$1, $ra, $1
 ; CHECK-NEXT:    32:	ff fd 00 00 	lw	$ra, 0($sp)
 ; CHECK-NEXT:    36:	00 01 0f 3c 	jr	$1
@@ -27,7 +27,7 @@
 ; CHECK-NEXT:    56:	fb fd 00 00 	sw	$ra, 0($sp)
 ; CHECK-NEXT:    5a:	41 a1 00 01 	lui	$1, 1
 ; CHECK-NEXT:    5e:	40 60 00 02 	bal	8 <foo+0x66>
-; CHECK-NEXT:    62:	30 21 04 5c 	addiu	$1, $1, 1116
+; CHECK-NEXT:    62:	30 21 04 5d 	addiu	$1, $1, 1117
 ; CHECK-NEXT:    66:	00 3f 09 50 	addu	$1, $ra, $1
 ; CHECK-NEXT:    6a:	ff fd 00 00 	lw	$ra, 0($sp)
 ; CHECK-NEXT:    6e:	00 01 0f 3c 	jr	$1
@@ -39,7 +39,7 @@
 ; CHECK-NEXT:    86:	fb fd 00 00 	sw	$ra, 0($sp)
 ; CHECK-NEXT:    8a:	41 a1 00 01 	lui	$1, 1
 ; CHECK-NEXT:    8e:	40 60 00 02 	bal	8 <foo+0x96>
-; CHECK-NEXT:    92:	30 21 04 2c 	addiu	$1, $1, 1068
+; CHECK-NEXT:    92:	30 21 04 2d 	addiu	$1, $1, 1069
 ; CHECK-NEXT:    96:	00 3f 09 50 	addu	$1, $ra, $1
 ; CHECK-NEXT:    9a:	ff fd 00 00 	lw	$ra, 0($sp)
 ; CHECK-NEXT:    9e:	00 01 0f 3c 	jr	$1
@@ -51,7 +51,7 @@
 ; CHECK-NEXT: 10476:	fb fd 00 00 	sw	$ra, 0($sp)
 ; CHECK-NEXT: 1047a:	41 a1 00 01 	lui	$1, 1
 ; CHECK-NEXT: 1047e:	40 60 00 02 	bal	8 <foo+0x10486>
-; CHECK-NEXT: 10482:	30 21 04 00 	addiu	$1, $1, 1024
+; CHECK-NEXT: 10482:	30 21 04 01 	addiu	$1, $1, 1025
 ; CHECK-NEXT: 10486:	00 3f 09 50 	addu	$1, $ra, $1
 ; CHECK-NEXT: 1048a:	ff fd 00 00 	lw	$ra, 0($sp)
 ; CHECK-NEXT: 1048e:	00 01 0f 3c 	jr	$1
Index: lib/MC/MCExpr.cpp
===================================================================
--- lib/MC/MCExpr.cpp
+++ lib/MC/MCExpr.cpp
@@ -558,6 +558,11 @@
   if (Asm->isThumbFunc(&SA))
     Addend |= 1;
 
+  // If symbol is labeled as micromips, we set low-bit to ensure
+  // correct offset in .gcc_except_table
+  if (Asm->getBackend().isMicroMips(&SA))
+    Addend |= 1;
+
   // Clear the symbol expr pointers to indicate we have folded these
   // operands.
   A = B = nullptr;


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