diff options
| -rw-r--r-- | gcc/ChangeLog | 6 | ||||
| -rw-r--r-- | gcc/testsuite/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.dg/torture/pr91812.c | 26 | ||||
| -rw-r--r-- | gcc/tree-ssa-phiprop.c | 11 |
4 files changed, 46 insertions, 2 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index c51b6f6..1810fe9 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2019-09-19 Richard Biener <rguenther@suse.de> + + PR tree-optimization/91812 + * tree-ssa-phiprop.c (propagate_with_phi): Do not replace + volatile loads. + 2019-09-19 Richard Sandiford <richard.sandiford@arm.com> * defaults.h (TARGET_UNIT): New macro. diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 07adb11..c5854bd 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2019-09-19 Richard Biener <rguenther@suse.de> + + PR tree-optimization/91812 + * gcc.dg/torture/pr91812.c: New testcase. + 2019-09-19 Tom Tromey <tromey@adacore.com> * gnat.dg/bias1.adb: New testcase. diff --git a/gcc/testsuite/gcc.dg/torture/pr91812.c b/gcc/testsuite/gcc.dg/torture/pr91812.c new file mode 100644 index 0000000..ebc67a0 --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/pr91812.c @@ -0,0 +1,26 @@ +/* { dg-do compile } */ +/* { dg-skip-if "" { *-*-* } { "-fno-fat-lto-objects" } { "" } } */ +/* { dg-options "-fdump-tree-optimized-blocks" } */ + +unsigned register1; +unsigned register2; + +void busy_wait_for_register (int x) +{ + volatile unsigned* ptr; + switch(x) { + case 0x1111: + ptr = ®ister1; + break; + + case 0x2222: + ptr = ®ister2; + break; + + default: + return; + } + while (*ptr) {} +} + +/* { dg-final { scan-tree-dump "loop depth 1" "optimized" } } */ diff --git a/gcc/tree-ssa-phiprop.c b/gcc/tree-ssa-phiprop.c index d710582..e90ae6a 100644 --- a/gcc/tree-ssa-phiprop.c +++ b/gcc/tree-ssa-phiprop.c @@ -338,8 +338,15 @@ propagate_with_phi (basic_block bb, gphi *phi, struct phiprop_d *phivn, && (!type || types_compatible_p (TREE_TYPE (gimple_assign_lhs (use_stmt)), type)) - /* We cannot replace a load that may throw or is volatile. */ - && !stmt_can_throw_internal (cfun, use_stmt))) + /* We cannot replace a load that may throw or is volatile. + For volatiles the transform can change the number of + executions if the load is inside a loop but the address + computations outside (PR91812). We could relax this + if we guard against that appropriately. For loads that can + throw we could relax things if the moved loads all are + known to not throw. */ + && !stmt_can_throw_internal (cfun, use_stmt) + && !gimple_has_volatile_ops (use_stmt))) continue; /* Check if we can move the loads. The def stmt of the virtual use |