Fix alignment in AArch64InstructionSelector::emitConstantPoolEntry()

The code was using the alignment of a pointer to the value, not the
alignment of the constant itself.

Maybe we got away with it so far because the pointer alignment is
fairly high, but we did end up under-aligning <16 x i8> vectors,
which was caught in the Chromium build after lld stopped over-aligning
the .rodata.cst16 section in r356428. (See crbug.com/953815)

Differential revision: https://reviews.llvm.org/D61124

llvm-svn: 359287

diff --git a/llvm/lib/Target/AArch64/AArch64InstructionSelector.cpp b/llvm/lib/Target/AArch64/AArch64InstructionSelector.cpp
index 51501c1..8a3310b 100644 (file)
--- a/llvm/lib/Target/AArch64/AArch64InstructionSelector.cpp
+++ b/llvm/lib/Target/AArch64/AArch64InstructionSelector.cpp
@@ -2572,7 +2572,7 @@ void AArch64InstructionSelector::collectShuffleMaskIndices(
 unsigned
 AArch64InstructionSelector::emitConstantPoolEntry(Constant *CPVal,
                                                   MachineFunction &MF) const {
-  Type *CPTy = CPVal->getType()->getPointerTo();
+  Type *CPTy = CPVal->getType();
   unsigned Align = MF.getDataLayout().getPrefTypeAlignment(CPTy);
   if (Align == 0)
     Align = MF.getDataLayout().getTypeAllocSize(CPTy);

diff --git a/llvm/test/CodeGen/AArch64/GlobalISel/select-shuffle-vector.mir b/llvm/test/CodeGen/AArch64/GlobalISel/select-shuffle-vector.mir
index 008c43f..20f3c38 100644 (file)
--- a/llvm/test/CodeGen/AArch64/GlobalISel/select-shuffle-vector.mir
+++ b/llvm/test/CodeGen/AArch64/GlobalISel/select-shuffle-vector.mir
@@ -82,7 +82,7 @@ body:             |
     ; CHECK-LABEL: name: shuffle_v4i32
     ; CHECK: constants:
     ; CHECK: value:           '<16 x i8> <i8 0, i8 1, i8 2, i8 3, i8 4, i8 5, i8 6, i8 7, i8 12, i8 13, i8 14, i8 15, i8 0, i8 1, i8 2, i8 3>'
-    ; CHECK: alignment:       8
+    ; CHECK: alignment:       16
     ; CHECK: isTargetSpecific: false
     ; CHECK: liveins: $q0, $q1
     ; CHECK: [[COPY:%[0-9]+]]:fpr128 = COPY $q0
@@ -117,7 +117,7 @@ body:             |
     ; CHECK-LABEL: name: shuffle_tbl_v4i32
     ; CHECK: constants:
     ; CHECK: value:           '<16 x i8> <i8 20, i8 21, i8 22, i8 23, i8 28, i8 29, i8 30, i8 31, i8 4, i8 5, i8 6, i8 7, i8 0, i8 1, i8 2, i8 3>'
-    ; CHECK: alignment:       8
+    ; CHECK: alignment:       16
     ; CHECK: isTargetSpecific: false
     ; CHECK: liveins: $q0, $q1
     ; CHECK: [[COPY:%[0-9]+]]:fpr128 = COPY $q0
@@ -153,7 +153,7 @@ body:             |
     ; CHECK-LABEL: name: shuffle_v2i64
     ; CHECK: constants:
     ; CHECK: value:           '<16 x i8> <i8 0, i8 1, i8 2, i8 3, i8 4, i8 5, i8 6, i8 7, i8 0, i8 1, i8 2, i8 3, i8 4, i8 5, i8 6, i8 7>'
-    ; CHECK: alignment:       8
+    ; CHECK: alignment:       16
     ; CHECK: isTargetSpecific: false
     ; CHECK: liveins: $q0, $q1
     ; CHECK: [[COPY:%[0-9]+]]:fpr128 = COPY $q0