This may be a test suite configuration error as the normal case works (and indeed I get a lot of profiled case failures of other cases). When run with an llvm-perf build of the HEAD, I get:

=====> T7837(normal) 1395 of 4068 [0, 0, 0] 
cd ./indexed-types/should_compile && '/Users/jrp/Projects/haskell/ghc/inplace/bin/ghc-stage2' -fforce-recomp -dcore-lint -dcmm-lint -dno-debug-output -no-user-package-db -rtsopts -fno-ghci-history -c T7837.hs  -O -ddump-rule-firings  >T7837.comp.stderr 2>&1
=====> T7837(profasm) 1395 of 4068 [0, 0, 0] 
cd ./indexed-types/should_compile && '/Users/jrp/Projects/haskell/ghc/inplace/bin/ghc-stage2' -fforce-recomp -dcore-lint -dcmm-lint -dno-debug-output -no-user-package-db -rtsopts -fno-ghci-history -c T7837.hs -O -prof -static -auto-all -O -ddump-rule-firings  >T7837.comp.stderr 2>&1
Actual stderr output differs from expected:
--- ./indexed-types/should_compile/T7837.stderr	2014-08-03 11:36:53.000000000 +0100
+++ ./indexed-types/should_compile/T7837.comp.stderr	2014-08-04 23:16:34.000000000 +0100
@@ -1,3 +1,4 @@
 Rule fired: Class op abs
 Rule fired: Class op signum
 Rule fired: normalize/Double
+Rule fired: Class op /
*** unexpected failure for T7837(profasm)

Unexpected results from:
TEST="T7837"

OVERALL SUMMARY for test run started at Mon Aug  4 23:16:32 2014 BST
 0:00:02 spent to go through
    4068 total tests, which gave rise to
   19536 test cases, of which
   19534 were skipped

       0 had missing libraries
       1 expected passes
       0 expected failures

       0 caused framework failures
       0 unexpected passes
       1 unexpected failures

Unexpected failures:
   indexed-types/should_compile  T7837 [stderr mismatch] (profasm)