Commit c6205397 authored by Martin Storsjö's avatar Martin Storsjö Committed by Tom Stellard
Browse files

[AArch64] Fix the upper limit for folded address offsets for COFF

In COFF, the immediates in IMAGE_REL_ARM64_PAGEBASE_REL21 relocations
are limited to 21 bit signed, i.e. the offset has to be less than
(1 << 20). The previous limit did intend to cover for this case, but
had missed that the 21 bit field was signed.

This fixes issue https://github.com/llvm/llvm-project/issues/54753.

Differential Revision: https://reviews.llvm.org/D123160

(cherry picked from commit 8d7a17b7)
parent 6697c5bc
......@@ -17115,13 +17115,14 @@ static SDValue performGlobalAddressCombine(SDNode *N, SelectionDAG &DAG,
 
// Check whether folding this offset is legal. It must not go out of bounds of
// the referenced object to avoid violating the code model, and must be
// smaller than 2^21 because this is the largest offset expressible in all
// object formats.
// smaller than 2^20 because this is the largest offset expressible in all
// object formats. (The IMAGE_REL_ARM64_PAGEBASE_REL21 relocation in COFF
// stores an immediate signed 21 bit offset.)
//
// This check also prevents us from folding negative offsets, which will end
// up being treated in the same way as large positive ones. They could also
// cause code model violations, and aren't really common enough to matter.
if (Offset >= (1 << 21))
if (Offset >= (1 << 20))
return SDValue();
 
const GlobalValue *GV = GN->getGlobal();
......
......@@ -162,13 +162,14 @@ static bool matchFoldGlobalOffset(MachineInstr &MI, MachineRegisterInfo &MRI,
// Check whether folding this offset is legal. It must not go out of bounds of
// the referenced object to avoid violating the code model, and must be
// smaller than 2^21 because this is the largest offset expressible in all
// object formats.
// smaller than 2^20 because this is the largest offset expressible in all
// object formats. (The IMAGE_REL_ARM64_PAGEBASE_REL21 relocation in COFF
// stores an immediate signed 21 bit offset.)
//
// This check also prevents us from folding negative offsets, which will end
// up being treated in the same way as large positive ones. They could also
// cause code model violations, and aren't really common enough to matter.
if (NewOffset >= (1 << 21))
if (NewOffset >= (1 << 20))
return false;
Type *T = GV->getValueType();
......
......@@ -84,23 +84,23 @@ define [2 x i64] @f4() {
define i64 @f5() {
; CHECK-LABEL: f5:
; CHECK: // %bb.0:
; CHECK-NEXT: adrp x8, x2+2097144
; CHECK-NEXT: ldr x0, [x8, :lo12:x2+2097144]
; CHECK-NEXT: adrp x8, x2+1048568
; CHECK-NEXT: ldr x0, [x8, :lo12:x2+1048568]
; CHECK-NEXT: ret
;
; GISEL-LABEL: f5:
; GISEL: // %bb.0:
; GISEL-NEXT: adrp x8, x2+2097144
; GISEL-NEXT: ldr x0, [x8, :lo12:x2+2097144]
; GISEL-NEXT: adrp x8, x2+1048568
; GISEL-NEXT: ldr x0, [x8, :lo12:x2+1048568]
; GISEL-NEXT: ret
%l = load i64, i64* getelementptr ([16777216 x i64], [16777216 x i64]* @x2, i64 0, i64 262143)
%l = load i64, i64* getelementptr ([16777216 x i64], [16777216 x i64]* @x2, i64 0, i64 131071)
ret i64 %l
}
define i64 @f6() {
; CHECK-LABEL: f6:
; CHECK: // %bb.0:
; CHECK-NEXT: mov w8, #2097152
; CHECK-NEXT: mov w8, #1048576
; CHECK-NEXT: adrp x9, x2
; CHECK-NEXT: add x9, x9, :lo12:x2
; CHECK-NEXT: ldr x0, [x9, x8]
......@@ -108,12 +108,12 @@ define i64 @f6() {
;
; GISEL-LABEL: f6:
; GISEL: // %bb.0:
; GISEL-NEXT: mov w8, #2097152
; GISEL-NEXT: mov w8, #1048576
; GISEL-NEXT: adrp x9, x2
; GISEL-NEXT: add x9, x9, :lo12:x2
; GISEL-NEXT: ldr x0, [x9, x8]
; GISEL-NEXT: ret
%l = load i64, i64* getelementptr ([16777216 x i64], [16777216 x i64]* @x2, i64 0, i64 262144)
%l = load i64, i64* getelementptr ([16777216 x i64], [16777216 x i64]* @x2, i64 0, i64 131072)
ret i64 %l
}
......
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