[ARM] Support constant pools in data when generating execute-only code.

Resubmission of r305387, which was reverted at r305390. The Address
Sanitizer caught a stack-use-after-scope of a Twine variable. This
is now fixed by passing the Twine directly as a function parameter.

The ARM backend asserts against constant pool lowering when it generates
execute-only code in order to prevent the generation of constant pools in
the text section. It appears that target independent optimizations might
generate DAG nodes that represent constant pools. By lowering such nodes
as global addresses we don't violate the semantics of execute-only code
and also it is guaranteed that execute-only behaves correct with the
position-independent addressing modes that support execute-only code.

Differential Revision: https://reviews.llvm.org/D33773

llvm-svn: 305776

1 files changed, 50 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/ARM/constantfp.ll b/llvm/test/CodeGen/ARM/constantfp.ll
index b5aeadc05eb..0b431f47f50 100644
--- a/llvm/test/CodeGen/ARM/constantfp.ll
+++ b/llvm/test/CodeGen/ARM/constantfp.ll
@@ -11,6 +11,9 @@
 ; RUN: llc -mtriple=thumbv7meb -arm-execute-only -mcpu=cortex-m4 %s -o - \
 ; RUN: | FileCheck --check-prefix=CHECK-XO-FLOAT --check-prefix=CHECK-XO-DOUBLE-BE %s
 
+; RUN: llc -mtriple=thumbv7m -arm-execute-only -mcpu=cortex-m4 -relocation-model=ropi %s -o - \
+; RUN: | FileCheck --check-prefix=CHECK-XO-ROPI %s
+
 ; RUN: llc -mtriple=thumbv8m.main -mattr=fp-armv8 %s -o - \
 ; RUN: | FileCheck --check-prefix=CHECK-NO-XO %s
 
@@ -20,6 +23,8 @@
 ; RUN: llc -mtriple=thumbv8m.maineb -arm-execute-only -mattr=fp-armv8 %s -o - \
 ; RUN: | FileCheck --check-prefix=CHECK-XO-FLOAT --check-prefix=CHECK-XO-DOUBLE-BE %s
 
+; RUN: llc -mtriple=thumbv8m.main -arm-execute-only -mattr=fp-armv8 -relocation-model=ropi %s -o - \
+; RUN: | FileCheck --check-prefix=CHECK-XO-ROPI %s
 
 define arm_aapcs_vfpcc float @test_vmov_f32() {
 ; CHECK-LABEL: test_vmov_f32:
@@ -176,3 +181,48 @@ define arm_aapcs_vfpcc double @lower_const_f64_xo() {
 ; CHECK-XO-DOUBLE-BE-NOT: vldr
   ret double 3.140000e-01
 }
+
+; This is a target independent optimization, performed by the
+; DAG Combiner, which promotes floating point literals into
+; constant pools:
+;
+; (a cond b) ? 1.0f : 2.0f -> load (ConstPoolAddr + ((a cond b) ? 0 : 4)
+;
+; We need to make sure that the constant pools are placed in
+; the data section when generating execute-only code:
+
+define arm_aapcs_vfpcc float @lower_fpconst_select(float %f) {
+
+; CHECK-NO-XO-LABEL: lower_fpconst_select
+; CHECK-NO-XO: adr [[REG:r[0-9]+]], [[LABEL:.?LCPI[0-9]+_[0-9]+]]
+; CHECK-NO-XO: vldr {{s[0-9]+}}, {{[[]}}[[REG]]{{[]]}}
+; CHECK-NO-XO-NOT: .rodata
+; CHECK-NO-XO: [[LABEL]]:
+; CHECK-NO-XO: .long   1335165689
+; CHECK-NO-XO: .long   1307470632
+
+; CHECK-XO-FLOAT-LABEL: lower_fpconst_select
+; CHECK-XO-FLOAT: movw [[REG:r[0-9]+]], :lower16:[[LABEL:.?LCP[0-9]+_[0-9]+]]
+; CHECK-XO-FLOAT: movt [[REG]], :upper16:[[LABEL]]
+; CHECK-XO-FLOAT: vldr {{s[0-9]+}}, {{[[]}}[[REG]]{{[]]}}
+; CHECK-XO-FLOAT: .rodata
+; CHECK-XO-FLOAT-NOT: .text
+; CHECK-XO-FLOAT: [[LABEL]]:
+; CHECK-XO-FLOAT: .long   1335165689
+; CHECK-XO-FLOAT: .long   1307470632
+
+; CHECK-XO-ROPI-LABEL: lower_fpconst_select
+; CHECK-XO-ROPI: movw [[REG:r[0-9]+]], :lower16:([[LABEL1:.?LCP[0-9]+_[0-9]+]]-([[LABEL2:.?LPC[0-9]+_[0-9]+]]+4))
+; CHECK-XO-ROPI: movt [[REG]], :upper16:([[LABEL1]]-([[LABEL2]]+4))
+; CHECK-XO-ROPI: [[LABEL2]]:
+; CHECK-XO-ROPI: vldr {{s[0-9]+}}, {{[[]}}[[REG]]{{[]]}}
+; CHECK-XO-ROPI: .rodata
+; CHECK-XO-ROPI-NOT: .text
+; CHECK-XO-ROPI: [[LABEL1]]:
+; CHECK-XO-ROPI: .long   1335165689
+; CHECK-XO-ROPI: .long   1307470632
+
+  %cmp = fcmp nnan oeq float %f, 0.000000e+00
+  %sel = select i1 %cmp, float 5.000000e+08, float 5.000000e+09
+  ret float %sel
+}