Bug 400490 s390x: Fix register allocation for VRs vs FPRs

On s390x, if vector registers are available, they are fed to the register
allocator as if they were separate from the floating-point registers.  But
in fact the FPRs are embedded in the VRs.  So for instance, if both f3 and
v3 are allocated and used at the same time, corruption will result.

This is fixed by offering only the non-overlapping VRs, v16 to v31, to the
register allocator instead.

diff --git a/NEWS b/NEWS
index 987d92857e012ebe50625a1ba149bce032583543..63287bb3b27ee9e6d1f8107d73ff8ca600e6dd04 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -47,6 +47,7 @@ where XXXXXX is the bug number as listed below.
 
 399301  Use inlined frames in Massif XTree output. 
 399322  Improve callgrind_annotate output
+400490  s390x: VRs allocated as if separate from FPRs
 
 Release 3.14.0 (9 October 2018)
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

diff --git a/VEX/priv/host_s390_defs.c b/VEX/priv/host_s390_defs.c
index 6c22ac8430db676e64208d9a55985fd64ae6b7f9..98ac9384dbbdee35e60a8bba05cc77d501a50b2a 100644 (file)
--- a/VEX/priv/host_s390_defs.c
+++ b/VEX/priv/host_s390_defs.c
@@ -59,7 +59,6 @@ static UInt s390_tchain_load64_len(void);
 
 /* A mapping from register number to register index */
 static Int gpr_index[16];  // GPR regno -> register index
-static Int fpr_index[16];  // FPR regno -> register index
 static Int vr_index[32];   // VR regno -> register index
 
 HReg
@@ -73,7 +72,7 @@ s390_hreg_gpr(UInt regno)
 HReg
 s390_hreg_fpr(UInt regno)
 {
-   Int ix = fpr_index[regno];
+   Int ix = vr_index[regno];
    vassert(ix >= 0);
    return mkHReg(/*virtual*/False, HRcFlt64, regno, ix);
 }
@@ -463,11 +462,9 @@ getRRegUniverse_S390(void)
 
    RRegUniverse__init(ru);
 
-   /* Assign invalid values to the gpr/fpr/vr_index */
+   /* Assign invalid values to the gpr/vr_index */
    for (UInt i = 0; i < sizeof gpr_index / sizeof gpr_index[0]; ++i)
       gpr_index[i] = -1;
-   for (UInt i = 0; i < sizeof fpr_index / sizeof fpr_index[0]; ++i)
-      fpr_index[i] = -1;
    for (UInt i = 0; i < sizeof vr_index / sizeof vr_index[0]; ++i)
       vr_index[i] = -1;
 
@@ -494,17 +491,17 @@ getRRegUniverse_S390(void)
 
    ru->allocable_start[HRcFlt64] = ru->size;
    for (UInt regno = 8; regno <= 15; ++regno) {
-      fpr_index[regno] = ru->size;
+      vr_index[regno] = ru->size;
       ru->regs[ru->size++] = s390_hreg_fpr(regno);
    }
    for (UInt regno = 0; regno <= 7; ++regno) {
-      fpr_index[regno] = ru->size;
+      vr_index[regno] = ru->size;
       ru->regs[ru->size++] = s390_hreg_fpr(regno);
    }
    ru->allocable_end[HRcFlt64] = ru->size - 1;
 
    ru->allocable_start[HRcVec128] = ru->size;
-   for (UInt regno = 0; regno <= 31; ++regno) {
+   for (UInt regno = 16; regno <= 31; ++regno) {
       vr_index[regno] = ru->size;
       ru->regs[ru->size++] = s390_hreg_vr(regno);
    }
@@ -527,12 +524,12 @@ getRRegUniverse_S390(void)
    /* Sanity checking */
    for (UInt i = 0; i < sizeof gpr_index / sizeof gpr_index[0]; ++i)
       vassert(gpr_index[i] >= 0);
-   for (UInt i = 0; i < sizeof fpr_index / sizeof fpr_index[0]; ++i)
-      vassert(fpr_index[i] >= 0);
    for (UInt i = 0; i < sizeof vr_index / sizeof vr_index[0]; ++i)
       vassert(vr_index[i] >= 0);
                  
    initialised = True;
+
+   RRegUniverse__check_is_sane(ru);
    return ru;
 }