[DebugInfo] Restore test case for long double constants.

[dgross]

Summary

D27549 (partial fix for PR26619) emits a constant value in the debug
metadata for a floating-point static const that does not exceed 64
bits in size. Whether or not a long double exceeds 64 bits in size
depends on the target. Modify the test case so that it expects a
constant value for long double if and only if the long double is no
larger than 64 bits.

[dgross]

I don't know exactly what the RUN syntax supported by lit is. What I've done here looks complex, but it does work for Linux. What about other platforms?

Is there some better way of writing a test case where the checks to be done by FileCheck depend on some property of the file being analyzed (here, the size of long double, as embedded in the debug metadata)? I don't see any support for conditions in FileCheck.

Maybe I'm going about this completely the wrong way?

[probinson]

As dblaikie said in email, probably better to make this X86-specific; if long-double varies by OS you can put in a specific triple.

FTR we don't rely on Perl being available everywhere, anything that does this kind of scripty stuff uses Python.

test/CodeGen/debug-info-static-const-fp.c

1–8

Sorry didn't notice this before, %clang is for driver tests only; use %clang_cc1 here.

[dgross]

In D27597#621596, @probinson wrote:

As dblaikie said in email, probably better to make this X86-specific; if long-double varies by OS you can put in a specific triple.

I think with this approach I'd want two test cases that are identical except for consideration of long double size: One that specifies a target where long double is "small" and one where it is "large". Actually, I guess I could make this a single test case, but have two compile and two filecheck lines, specifying different triples, as you suggest. Or even three: One for whatever the default target is (doesn't check long double), one for a triple where long double is small, and one for a triple where long double is large.

FTR we don't rely on Perl being available everywhere, anything that does this kind of scripty stuff uses Python.

So would a Python equivalent of the Perl be acceptable? I think this is an academic question -- better to explicitly test multiple triples.

[dgross]

Incorporate code review comments.

• Use %clang_cc1 not %clang
• Rather than trying to determine long double size for target, compile and check multiple times, and only check behavior of long double for known targets

[probinson]

In D27597#621618, @dgross wrote:

So would a Python equivalent of the Perl be acceptable? I think this is an academic question -- better to explicitly test multiple triples.

There are a small number of tests that run Python scripts, but they are generally doing something really unusual (I admit I haven't gone to look, but that's my recollection). If you can get proper coverage without Python, and it doesn't require standing on your head, people generally prefer that. In this case, multiple RUNs with different triples will do the job, so that's preferable.

LGTM.

test/CodeGen/debug-info-static-const-fp.c

-// RUN: %clang -emit-llvm -O0 -S -g %s -o - | FileCheck %s
+// RUN: %clang_cc1 -emit-llvm -O0 -debug-info-kind=limited %s -o - | \
+// RUN:   FileCheck --check-prefixes CHECK %s
+
+// RUN: %clang_cc1 -triple hexagon-unknown--elf -emit-llvm -O0 -debug-info-kind=limited %s -o - | \
+// RUN:   FileCheck --check-prefixes CHECK,CHECK-LDsm %s
+
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm -O0 -debug-info-kind=limited %s -o - | \
+// RUN:   FileCheck --check-prefixes CHECK,CHECK-LDlg %s
 
 // Per PR26619, check that for referenced static const of floating-point type,
-// we emit its constant value in debug info.  NOTE that PR26619 is not yet fixed for long double.
+// we emit its constant value in debug info.
+//
+// NOTE that __fp16 is assumed to be 16 bits, float is assumed to be
+// 32 bits, and double is assumed to be 64 bits.  Size of long double
+// is not known (for example, it is 64 bits for hexagon-unknown--elf,
+// but 128 bits for x86_64-unknown-linux-gnu).  Therefore, we specify
+// target triples where it has a known size, and check accordingly:
+// for the absence of a constant (CHECK-LDlg) when the size exceeds 64
+// bits, and for the presence of a constant (CHECK-LDsm) but not its
+// value when the size does not exceed 64 bits.
+//
+// NOTE that PR26619 is not yet fixed for types greater than 64 bits.
 
 static const __fp16 hVal = 29/13.0f;            //    2.2307692307692307692     (2.23046875)
 
 static const float fVal = -147/17.0f;           //   -8.6470588235294117647     (-8.64705849)
 
 static const double dVal = 19637/7.0;           // 2805.2857142857142857        (2805.2857142857142)
 
-static const long double ldVal = 3/1234567.0L;  //    2.4300017739012949479e-06 (<optimized out>)
+static const long double ldVal = 3/1234567.0L;  //    2.4300017739012949479e-06 (<depends on size of long double>)
 
 int main() {
   return hVal + fVal + dVal + ldVal;
 }
 
 // CHECK: !DIGlobalVariable(name: "hVal", {{.*}}, isLocal: true, isDefinition: true, expr: ![[HEXPR:[0-9]+]]
 // CHECK: ![[HEXPR]] = !DIExpression(DW_OP_constu, 16502, DW_OP_stack_value)
 
 // CHECK: !DIGlobalVariable(name: "fVal", {{.*}}, isLocal: true, isDefinition: true, expr: ![[FEXPR:[0-9]+]]
 // CHECK: ![[FEXPR]] = !DIExpression(DW_OP_constu, 3238681178, DW_OP_stack_value)
 
 // CHECK: !DIGlobalVariable(name: "dVal", {{.*}}, isLocal: true, isDefinition: true, expr: ![[DEXPR:[0-9]+]]
 // CHECK: ![[DEXPR]] = !DIExpression(DW_OP_constu, 4658387303597904457, DW_OP_stack_value)
 
-// Temporarily removing this check -- for some targets (such as
-// "--target=hexagon-unknown-elf"), long double does not exceed 64
-// bits, and so we actually do get the constant value (expr) emitted.
-//
-// DO-NOT-CHECK: !DIGlobalVariable(name: "ldVal", {{.*}}, isLocal: true, isDefinition: true)
+// CHECK-LDlg: !DIGlobalVariable(name: "ldVal", {{.*}}, isLocal: true, isDefinition: true)
+// CHECK-LDsm: !DIGlobalVariable(name: "ldVal", {{.*}}, isLocal: true, isDefinition: true, expr: